.......... [ZBX-20859] updated to the latest master; no conflicts

30 files changed, 2316 insertions, 1604 deletions

diff --git a/.github/workflows/sonarcloud.yml b/.github/workflows/sonarcloud.yml
index ecd95aa8ed7..dc1e9086d74 100644
--- a/.github/workflows/sonarcloud.yml
+++ b/.github/workflows/sonarcloud.yml
@@ -15,7 +15,7 @@ jobs:
     env:
       SONAR_SCANNER_VERSION: 4.7.0.2747
       SONAR_SERVER_URL: "https://sonarcloud.io"
-      BUILD_WRAPPER_OUT_DIR: build_wrapper_output_directory # Directory where build-wrapper output will be placed
+      BUILD_WRAPPER_OUT_DIR: $HOME/.sonar/build_wrapper_output_directory # Directory where build-wrapper output will be placed
     steps:
       - uses: actions/checkout@v2
         with:
diff --git a/ChangeLog b/ChangeLog
index 84c13da75db..f8583af7920 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,6 +14,7 @@ A.F....... [ZBXNEXT-7476] disabled php 8 strict type validation (ashubin)
 A.F....... [ZBXNEXT-7491] fixed PHP 8.1 runtime warnings with PostgreSQL backend (Sasha)
 
 Bug fixes:
+..F....... [ZBX-20242] fixed inability to change LDAP bind password (agriscenko)
 ...G...... [ZBX-20911] added process state check in PROC_NUM() for Oracle Solaris (Andris)
 ..F....... [ZBX-20752] fixed saved properties of classic graphs being lost when reopening graph configuration (agriscenko)
 ..F....... [ZBX-19381] fixed resolving of macros in item key parameters when testing items in web interface (Sasha)
diff --git a/ChangeLog.d/bugfix/ZBX-20613 b/ChangeLog.d/bugfix/ZBX-20613
new file mode 100644
index 00000000000..3fded15f049
--- /dev/null
+++ b/ChangeLog.d/bugfix/ZBX-20613
@@ -0,0 +1 @@
+A.F....... [ZBX-20613] returned the ability to edit the dependencies of inherited triggers; improved validation upon unlinking templates with triggers that have dependencies; improved performance of trigger dependency functionality; prevented the ability to fully replace trigger dependencies of inherited triggers if the new dependency was added to parent trigger; supplemented validation of trigger dependencies on templates to prevent linkage dead-ends (vmaksimovs)
diff --git a/ChangeLog.d/bugfix/ZBX-20814 b/ChangeLog.d/bugfix/ZBX-20814
new file mode 100644
index 00000000000..5fb3ccd4389
--- /dev/null
+++ b/ChangeLog.d/bugfix/ZBX-20814
@@ -0,0 +1 @@
+..F....... [ZBX-20814] fixed Map->Sharing user group shares table not showing saved user groups (esekace)
diff --git a/ChangeLog.d/bugfix/ZBX-20898 b/ChangeLog.d/bugfix/ZBX-20898
new file mode 100644
index 00000000000..d630940c0b3
--- /dev/null
+++ b/ChangeLog.d/bugfix/ZBX-20898
@@ -0,0 +1 @@
+.........T [ZBX-20898] fixed duplicate UUID in official template (abakaldin)
diff --git a/templates/app/ftp_service/template_app_ftp_service.yaml b/templates/app/ftp_service/template_app_ftp_service.yaml
index 8e3d1e5223b..1fb9f225237 100644
--- a/templates/app/ftp_service/template_app_ftp_service.yaml
+++ b/templates/app/ftp_service/template_app_ftp_service.yaml
@@ -32,7 +32,7 @@ zabbix_export:
               value: network
           triggers:
             -
-              uuid: b299d73cebcd430c8bfc54cf9b84e853
+              uuid: aee485c125f94e37ac97c3ce1a654757
               expression: 'max(/FTP Service/net.tcp.service[ftp],#3)=0'
               name: 'FTP service is down on {HOST.NAME}'
               priority: AVERAGE
diff --git a/templates/db/postgresql_agent2/README.md b/templates/db/postgresql_agent2/README.md
index 88727664850..10b94efc64c 100644
--- a/templates/db/postgresql_agent2/README.md
+++ b/templates/db/postgresql_agent2/README.md
@@ -19,7 +19,7 @@ This template was tested on:
 1\. Create PostgreSQL user for monitoring (`<password>` at your discretion):
 
 ```bash
-CREATE USER 'zbx_monitor' WITH PASSWORD '<PASSWORD>' INHERIT;
+CREATE USER zbx_monitor WITH PASSWORD '<PASSWORD>' INHERIT;
 GRANT EXECUTE ON FUNCTION pg_catalog.pg_ls_dir(text) TO zbx_monitor;
 GRANT EXECUTE ON FUNCTION pg_catalog.pg_stat_file(text) TO zbx_monitor;
 GRANT EXECUTE ON FUNCTION pg_catalog.pg_ls_waldir() TO zbx_monitor;
diff --git a/ui/app/controllers/CControllerAuthenticationEdit.php b/ui/app/controllers/CControllerAuthenticationEdit.php
index e4b6d51d1c5..c7807cec589 100644
--- a/ui/app/controllers/CControllerAuthenticationEdit.php
+++ b/ui/app/controllers/CControllerAuthenticationEdit.php
@@ -92,8 +92,6 @@ class CControllerAuthenticationEdit extends CController {
 		$openssl_status = (new CFrontendSetup())->checkPhpOpenSsl();
 
 		$data = [
-			'action_submit' => 'authentication.update',
-			'action_passw_change' => 'authentication.edit',
 			'ldap_error' => ($ldap_status['result'] == CFrontendSetup::CHECK_OK) ? '' : $ldap_status['error'],
 			'ldap_test_password' => '',
 			'ldap_test_user' => CWebUser::$data['username'],
diff --git a/ui/app/controllers/CControllerHostCreate.php b/ui/app/controllers/CControllerHostCreate.php
index 89565b41cd9..c7f835922d0 100644
--- a/ui/app/controllers/CControllerHostCreate.php
+++ b/ui/app/controllers/CControllerHostCreate.php
@@ -106,11 +106,11 @@ class CControllerHostCreate extends CControllerHostUpdateGeneral {
 				$host = $this->extendHostCloneEncryption($host, $src_hostid);
 			}
 
-			$hostids = API::Host()->create($host);
+			$result = API::Host()->create($host);
 
-			if ($hostids === false
-					|| !$this->createValueMaps($hostids['hostids'][0])
-					|| ($full_clone && !$this->copyFromCloneSourceHost($src_hostid, $hostids['hostids'][0]))) {
+			if ($result === false
+					|| !$this->createValueMaps($result['hostids'][0])
+					|| ($full_clone && !$this->copyFromCloneSourceHost($src_hostid, $result['hostids'][0]))) {
 				throw new Exception();
 			}
 
@@ -210,14 +210,7 @@ class CControllerHostCreate extends CControllerHostUpdateGeneral {
 		}
 
 		// Copy triggers.
-		$db_triggers = API::Trigger()->get([
-			'output' => ['triggerid'],
-			'hostids' => $src_hostid,
-			'inherited' => false,
-			'filter' => ['flags' => ZBX_FLAG_DISCOVERY_NORMAL]
-		]);
-
-		if ($db_triggers && !copyTriggersToHosts(array_column($db_triggers, 'triggerid'), $hostid, $src_hostid)) {
+		if (!copyTriggersToHosts([$hostid], $src_hostid)) {
 			return false;
 		}
 
diff --git a/ui/app/views/administration.authentication.edit.php b/ui/app/views/administration.authentication.edit.php
index 1f6d1385d7a..0d18f9075fb 100644
--- a/ui/app/views/administration.authentication.edit.php
+++ b/ui/app/views/administration.authentication.edit.php
@@ -136,19 +136,23 @@ $http_tab = (new CFormList('list_http'))
 
 // LDAP configuration fields.
 if ($data['change_bind_password']) {
-	$password_box = [
-		new CVar('change_bind_password', 1),
-		(new CPassBox('ldap_bind_password', $data['ldap_bind_password']))
-			->setEnabled($data['ldap_enabled'])
-			->setWidth(ZBX_TEXTAREA_SMALL_WIDTH)
-	];
+	$password_box = (new CPassBox('ldap_bind_password', $data['ldap_bind_password'],
+		DB::getFieldLength('config', 'ldap_bind_password'))
+	)
+		->setEnabled($data['ldap_enabled'])
+		->setWidth(ZBX_TEXTAREA_SMALL_WIDTH)
+	;
 }
 else {
 	$password_box = [
-		new CVar('action_passw_change', $data['action_passw_change']),
-		(new CButton('change_bind_password', _('Change password')))
+		(new CSimpleButton(_('Change password')))
+			->setId('bind-password-btn')
 			->setEnabled($data['ldap_enabled'])
-			->addClass(ZBX_STYLE_BTN_GREY)
+			->addClass(ZBX_STYLE_BTN_GREY),
+		(new CPassBox('ldap_bind_password', '', DB::getFieldLength('config', 'ldap_bind_password')))
+			->setWidth(ZBX_TEXTAREA_SMALL_WIDTH)
+			->addClass(ZBX_STYLE_DISPLAY_NONE)
+			->setEnabled(false)
 	];
 }
 
@@ -322,7 +326,8 @@ $saml_tab = (new CFormList('list_saml'))
 (new CWidget())
 	->setTitle(_('Authentication'))
 	->addItem((new CForm())
-		->addVar('action', $data['action_submit'])
+		->addVar('action', 'authentication.update')
+		->addVar('change_bind_password', $data['change_bind_password'])
 		->addVar('db_authentication_type', $data['db_authentication_type'])
 		->setId('authentication-form')
 		->setName('form_auth')
diff --git a/ui/app/views/js/administration.authentication.edit.js.php b/ui/app/views/js/administration.authentication.edit.js.php
index 1baac8907f4..1b8d80a1b84 100644
--- a/ui/app/views/js/administration.authentication.edit.js.php
+++ b/ui/app/views/js/administration.authentication.edit.js.php
@@ -51,7 +51,7 @@
 				fields = $form.find('[name^=http_]');
 			}
 			else if ($(this).is('#ldap_configured')) {
-				fields = $form.find('[name^=ldap_],button[name=change_bind_password]');
+				fields = $form.find('[name^=ldap_],#bind-password-btn');
 			}
 			else {
 				fields = $form.find('[name^=saml_]');
@@ -62,15 +62,22 @@
 				.prop('disabled', !this.checked);
 		});
 
-		$form.find('button#change_bind_password').click(function() {
-			$form.find('[name=action]')
-				.val($form.find('[name=action_passw_change]').val());
-
-			submitFormWithParam('form_auth', 'change_bind_password', '1');
-		});
+		$form.find('#bind-password-btn').on('click', showPasswordField);
 
 		$form.find('[name=ldap_test]').click(function() {
 			warn = false;
 		});
 	});
+
+	function showPasswordField(e) {
+		const form_field = e.target.parentNode;
+		const password_field = form_field.querySelector('[name="ldap_bind_password"]');
+
+		password_field.disabled = false;
+		password_field.classList.remove('<?= ZBX_STYLE_DISPLAY_NONE ?>');
+
+		form_field.removeChild(e.target);
+
+		document.getElementById('change_bind_password').value = 1;
+	}
 </script>
diff --git a/ui/include/classes/api/services/CDiscoveryRule.php b/ui/include/classes/api/services/CDiscoveryRule.php
index 7d906a2ebc8..fe91fd2520e 100644
--- a/ui/include/classes/api/services/CDiscoveryRule.php
+++ b/ui/include/classes/api/services/CDiscoveryRule.php
@@ -714,196 +714,225 @@ class CDiscoveryRule extends CItemGeneral {
 	/**
 	 * Copies all of the triggers from the source discovery to the target discovery rule.
 	 *
-	 * @throws APIException if trigger saving fails
-	 *
-	 * @param array $srcDiscovery    The source discovery rule to copy from
-	 * @param array $srcHost         The host the source discovery belongs to
-	 * @param array $dstHost         The host the target discovery belongs to
+	 * @param array  $src_discovery       The source discovery rule to copy from.
+	 * @param array  $src_host            The host the source discovery belongs to.
+	 * @param string $src_host['hostid']
+	 * @param string $src_host['host']
+	 * @param array  $dst_host            The host the target discovery belongs to.
+	 * @param string $dst_host['hostid']
+	 * @param string $dst_host['host']
 	 *
 	 * @return array
+	 *
+	 * @throws APIException
 	 */
-	protected function copyTriggerPrototypes(array $srcDiscovery, array $srcHost, array $dstHost) {
-		$srcTriggers = API::TriggerPrototype()->get([
-			'discoveryids' => $srcDiscovery['itemid'],
-			'output' => ['triggerid', 'expression', 'description', 'url', 'status', 'priority', 'comments',
-				'templateid', 'type', 'recovery_mode', 'recovery_expression', 'correlation_mode', 'correlation_tag',
-				'opdata', 'discover', 'event_name'
+	protected function copyTriggerPrototypes(array $src_discovery, array $src_host, array $dst_host): array {
+		$src_triggers = API::TriggerPrototype()->get([
+			'output' => ['triggerid', 'expression', 'description', 'url', 'status', 'priority', 'comments', 'type',
+				'recovery_mode', 'recovery_expression', 'correlation_mode', 'correlation_tag', 'opdata', 'discover',
+				'event_name'
 			],
-			'selectHosts' => API_OUTPUT_EXTEND,
 			'selectItems' => ['itemid', 'type'],
-			'selectDiscoveryRule' => API_OUTPUT_EXTEND,
-			'selectFunctions' => API_OUTPUT_EXTEND,
-			'selectDependencies' => ['triggerid'],
 			'selectTags' => ['tag', 'value'],
-			'preservekeys' => true
+			'selectDependencies' => ['triggerid'],
+			'discoveryids' => $src_discovery['itemid']
 		]);
 
-		foreach ($srcTriggers as $id => $trigger) {
+		$dst_triggers = [];
+
+		foreach ($src_triggers as $i => $src_trigger) {
 			// Skip trigger prototypes with web items and remove them from source.
-			if (httpItemExists($trigger['items'])) {
-				unset($srcTriggers[$id]);
+			if (httpItemExists($src_trigger['items'])) {
+				unset($src_triggers[$i]);
+			}
+			else {
+				$dst_triggers[] = array_intersect_key($src_trigger, array_flip(['expression', 'description', 'url',
+					'status', 'priority', 'comments','type', 'recovery_mode', 'recovery_expression', 'correlation_mode',
+					'correlation_tag', 'opdata', 'discover', 'event_name', 'tags'
+				]));
 			}
 		}
 
-		if (!$srcTriggers) {
+		if (!$dst_triggers) {
 			return [];
 		}
 
-		/*
-		 * Copy the remaining trigger prototypes to a new source. These will contain IDs and original dependencies.
-		 * The dependencies from $srcTriggers will be removed.
-		 */
-		$trigger_prototypes = $srcTriggers;
-
-		// Contains original trigger prototype dependency IDs.
-		$dep_triggerids = [];
-
-		/*
-		 * Collect dependency trigger IDs and remove them from source. Otherwise these IDs do not pass
-		 * validation, since they don't belong to destination discovery rule.
-		 */
-		$add_dependencies = false;
-
-		foreach ($srcTriggers as $id => &$trigger) {
-			if ($trigger['dependencies']) {
-				foreach ($trigger['dependencies'] as $dep_trigger) {
-					$dep_triggerids[] = $dep_trigger['triggerid'];
-				}
-				$add_dependencies = true;
-			}
-			unset($trigger['dependencies']);
-		}
-		unset($trigger);
+		$src_triggers = array_values($src_triggers);
 
-		// Save new trigger prototypes and without dependencies for now.
-		$dstTriggers = $srcTriggers;
-		$dstTriggers = CMacrosResolverHelper::resolveTriggerExpressions($dstTriggers,
+		$dst_triggers = CMacrosResolverHelper::resolveTriggerExpressions($dst_triggers,
 			['sources' => ['expression', 'recovery_expression']]
 		);
-		foreach ($dstTriggers as $id => &$trigger) {
-			unset($trigger['triggerid'], $trigger['templateid'], $trigger['hosts'], $trigger['functions'],
-				$trigger['items'], $trigger['discoveryRule']
-			);
 
-			// Update the destination expressions.
-			$trigger['expression'] = triggerExpressionReplaceHost($trigger['expression'], $srcHost['host'],
-				$dstHost['host']
+		foreach ($dst_triggers as &$trigger) {
+			$trigger['expression'] = triggerExpressionReplaceHost($trigger['expression'], $src_host['host'],
+				$dst_host['host']
 			);
+
 			if ($trigger['recovery_mode'] == ZBX_RECOVERY_MODE_RECOVERY_EXPRESSION) {
 				$trigger['recovery_expression'] = triggerExpressionReplaceHost($trigger['recovery_expression'],
-					$srcHost['host'], $dstHost['host']
+					$src_host['host'], $dst_host['host']
 				);
 			}
 		}
 		unset($trigger);
 
-		$result = API::TriggerPrototype()->create($dstTriggers);
+		$result = API::TriggerPrototype()->create($dst_triggers);
+
 		if (!$result) {
 			self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot clone trigger prototypes.'));
 		}
 
-		// Process dependencies, if at least one trigger prototype has a dependency.
-		if ($add_dependencies) {
-			$trigger_prototypeids = array_keys($trigger_prototypes);
+		$dst_triggerids = $result['triggerids'];
+		$src_trigger_indexes = array_flip(array_column($src_triggers, 'triggerid'));
 
-			foreach ($result['triggerids'] as $i => $triggerid) {
-				$new_trigger_prototypes[$trigger_prototypeids[$i]] = [
-					'new_triggerid' => $triggerid,
-					'new_hostid' => $dstHost['hostid'],
-					'new_host' => $dstHost['host'],
-					'src_hostid' => $srcHost['hostid'],
-					'src_host' => $srcHost['host']
-				];
+		$dst_triggers = [];
+
+		/*
+		 * A check that the trigger-up belongs to the source host needs to be performed on copying the dependencies
+		 * on triggers.
+		 * If it does, we need to check that the triggers with the same description and expression exist on the
+		 * destination host.
+		 * If not, we need to check if the dependencies from destination triggers to these triggers are valid.
+		 */
+		$src_triggerids_up = [];
+
+		foreach ($dst_triggerids as $i => $dst_triggerid) {
+			if (!$src_triggers[$i]['dependencies']) {
+				unset($dst_triggerids[$i]);
+				continue;
 			}
 
-			/*
-			 * Search for original dependent triggers and expressions to find corresponding triggers on destination host
-			 * with same expression.
-			 */
-			$dep_triggers = API::Trigger()->get([
-				'output' => ['description', 'expression'],
-				'selectHosts' => ['hostid'],
-				'triggerids' => $dep_triggerids,
-				'preservekeys' => true
-			]);
-			$dep_triggers = CMacrosResolverHelper::resolveTriggerExpressions($dep_triggers);
+			$dst_triggers[$dst_triggerid] = ['triggerid' => $dst_triggerid];
 
-			// Map dependencies to the new trigger IDs and save.
-			foreach ($trigger_prototypes as &$trigger_prototype) {
-				// Get corresponding created trigger prototype ID.
-				$new_trigger_prototype = $new_trigger_prototypes[$trigger_prototype['triggerid']];
+			foreach ($src_triggers[$i]['dependencies'] as $i2 => $src_trigger_up) {
+				if (array_key_exists($src_trigger_up['triggerid'], $src_trigger_indexes)) {
+					// Add dependency on the trigger prototype of the same LLD rule.
+					$dst_triggers[$dst_triggerid]['dependencies'][] =
+						['triggerid' => $result['triggerids'][$src_trigger_indexes[$src_trigger_up['triggerid']]]];
 
-				if ($trigger_prototype['dependencies']) {
-					foreach ($trigger_prototype['dependencies'] as &$dependency) {
-						$dep_triggerid = $dependency['triggerid'];
+					unset($src_triggers[$i]['dependencies'][$i2]);
+				}
+				else {
+					$src_triggerids_up[$src_trigger_up['triggerid']] = true;
+				}
+			}
 
-						/*
-						 * We have added a dependent trigger prototype and we know corresponding trigger prototype ID
-						 * for newly created trigger prototype.
-						 */
-						if (array_key_exists($dependency['triggerid'], $new_trigger_prototypes)) {
-							/*
-							 * Dependency is within same host according to $srcHostId parameter or dep trigger has
-							 * single host.
-							 */
-							if ($new_trigger_prototype['src_hostid'] ==
-									$new_trigger_prototypes[$dep_triggerid]['src_hostid']) {
-								$dependency['triggerid'] = $new_trigger_prototypes[$dep_triggerid]['new_triggerid'];
-							}
-						}
-						elseif (in_array(['hostid' => $new_trigger_prototype['src_hostid']],
-								$dep_triggers[$dep_triggerid]['hosts'])) {
-							// Get all possible $depTrigger matching triggers by description.
-							$target_triggers = API::Trigger()->get([
-								'output' => ['hosts', 'triggerid', 'expression'],
-								'hostids' => $new_trigger_prototype['new_hostid'],
-								'filter' => ['description' => $dep_triggers[$dep_triggerid]['description']],
-								'preservekeys' => true
-							]);
-							$target_triggers = CMacrosResolverHelper::resolveTriggerExpressions($target_triggers);
-
-							// Compare exploded expressions for exact match.
-							$expr1 = $dep_triggers[$dep_triggerid]['expression'];
-							$dependency['triggerid'] = null;
-
-							foreach ($target_triggers as $target_trigger) {
-								$expr2 = triggerExpressionReplaceHost($target_trigger['expression'],
-									$new_trigger_prototype['new_host'],
-									$new_trigger_prototype['src_host']
-								);
+			if (!$src_triggers[$i]['dependencies']) {
+				unset($dst_triggerids[$i]);
+			}
+		}
 
-								if ($expr2 === $expr1) {
-									// Matching trigger has been found.
-									$dependency['triggerid'] = $target_trigger['triggerid'];
-									break;
-								}
-							}
+		if ($src_triggerids_up) {
+			$src_host_triggers_up = DBfetchArrayAssoc(DBselect(
+				'SELECT DISTINCT t.triggerid,t.description,t.expression,t.recovery_expression'.
+				' FROM triggers t,functions f,items i'.
+				' WHERE t.triggerid=f.triggerid'.
+					' AND f.itemid=i.itemid'.
+					' AND '.dbConditionId('t.triggerid', array_keys($src_triggerids_up)).
+					' AND '.dbConditionId('i.hostid', [$src_host['hostid']])
+			), 'triggerid');
 
-							// If matching trigger was not found, raise exception.
-							if ($dependency['triggerid'] === null) {
-								$expr2 = triggerExpressionReplaceHost($dep_triggers[$dep_triggerid]['expression'],
-									$new_trigger_prototype['src_host'],
-									$new_trigger_prototype['new_host']
-								);
-								self::exception(ZBX_API_ERROR_PARAMETERS, _s(
-									'Cannot add dependency from trigger "%1$s:%2$s" to non existing trigger "%3$s:%4$s".',
-									$trigger_prototype['description'],
-									$trigger_prototype['expression'],
-									$dep_triggers[$dep_triggerid]['description'],
-									$expr2
-								));
-							}
+			$src_host_triggers_up = CMacrosResolverHelper::resolveTriggerExpressions($src_host_triggers_up,
+				['sources' => ['expression', 'recovery_expression']]
+			);
+
+			$src_host_dependencies = [];
+			$other_host_dependencies = [];
+
+			foreach ($dst_triggerids as $i => $dst_triggerid) {
+				$src_trigger = $src_triggers[$i];
+
+				foreach ($src_trigger['dependencies'] as $src_trigger_up) {
+					if (array_key_exists($src_trigger_up['triggerid'], $src_host_triggers_up)) {
+						$src_host_dependencies[$src_trigger_up['triggerid']][$src_trigger['triggerid']] = true;
+					}
+					else {
+						// Add dependency on the trigger of the other templates or hosts.
+						$dst_triggers[$dst_triggerid]['dependencies'][] = ['triggerid' => $src_trigger_up['triggerid']];
+						$other_host_dependencies[$src_trigger_up['triggerid']][$dst_triggerid] = true;
+					}
+				}
+			}
+
+			if ($src_host_dependencies) {
+				$dst_host_triggers = DBfetchArrayAssoc(DBselect(
+					'SELECT DISTINCT t.triggerid,t.description,t.expression,t.recovery_expression'.
+					' FROM items i,functions f,triggers t'.
+					' WHERE i.itemid=f.itemid'.
+						' AND f.triggerid=t.triggerid'.
+						' AND '.dbConditionId('i.hostid', [$dst_host['hostid']]).
+						' AND '.dbConditionString('t.description',
+							array_unique(array_column($src_host_triggers_up, 'description'))
+						)
+				), 'triggerid');
+
+				$dst_host_triggers = CMacrosResolverHelper::resolveTriggerExpressions($dst_host_triggers);
+
+				$dst_host_triggerids = [];
+
+				foreach ($dst_host_triggers as $i => $trigger) {
+					$expression = triggerExpressionReplaceHost($trigger['expression'], $dst_host['host'],
+						$src_host['host']
+					);
+					$recovery_expression = $trigger['recovery_expression'];
+
+					if ($recovery_expression !== '') {
+						$recovery_expression = triggerExpressionReplaceHost($trigger['recovery_expression'],
+							$dst_host['host'], $src_host['host']
+						);
+					}
+
+					$dst_host_triggerids[$trigger['description']][$expression][$recovery_expression] =
+						$trigger['triggerid'];
+				}
+
+				foreach ($src_host_triggers_up as $src_trigger_up) {
+					$description = $src_trigger_up['description'];
+					$expression = $src_trigger_up['expression'];
+					$recovery_expression = $src_trigger_up['recovery_expression'];
+
+					if (array_key_exists($description, $dst_host_triggerids)
+							&& array_key_exists($expression, $dst_host_triggerids[$description])
+							&& array_key_exists($recovery_expression, $dst_host_triggerids[$description][$expression])) {
+						$dst_triggerid_up = $dst_host_triggerids[$description][$expression][$recovery_expression];
+
+						foreach ($src_host_dependencies[$src_trigger_up['triggerid']] as $src_triggerid => $foo) {
+							$dst_triggerid = $dst_triggerids[$src_trigger_indexes[$src_triggerid]];
+
+							$dst_triggers[$dst_triggerid]['dependencies'][] = ['triggerid' => $dst_triggerid_up];
 						}
 					}
-					unset($dependency);
+					else {
+						$src_triggerid = key($src_host_dependencies[$src_trigger_up['triggerid']]);
+						$src_trigger = $src_triggers[$src_trigger_indexes[$src_triggerid]];
+
+						$hosts = DB::select('hosts', [
+							'output' => ['status'],
+							'hostids' => $dst_host['hostid']
+						]);
 
-					$trigger_prototype['triggerid'] = $new_trigger_prototype['new_triggerid'];
+						$error = ($hosts[0]['status'] == HOST_STATUS_TEMPLATE)
+							? _('Trigger prototype "%1$s" cannot depend on the non-existent trigger "%2$s" on the template "%3$s".')
+							: _('Trigger prototype "%1$s" cannot depend on the non-existent trigger "%2$s" on the host "%3$s".');
+
+						self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $src_trigger['description'],
+							$src_trigger_up['description'], $dst_host['host']
+						));
+					}
 				}
 			}
-			unset($trigger_prototype);
 
-			// If adding a dependency fails, the exception will be raised in TriggerPrototype API.
-			API::TriggerPrototype()->addDependencies($trigger_prototypes);
+			if ($other_host_dependencies) {
+				$trigger_hosts = CTriggerGeneral::getTriggerHosts($other_host_dependencies);
+
+				CTriggerGeneral::checkDependenciesOfHostTriggers($other_host_dependencies, $trigger_hosts);
+				CTriggerGeneral::checkDependenciesOfTemplateTriggers($other_host_dependencies, $trigger_hosts);
+			}
+		}
+
+		if ($dst_triggers) {
+			$dst_triggers = array_values($dst_triggers);
+			CTriggerGeneral::updateDependencies($dst_triggers);
 		}
 
 		return $result;
diff --git a/ui/include/classes/api/services/CHostBase.php b/ui/include/classes/api/services/CHostBase.php
index 8d05cc8225c..14c0f2bf742 100644
--- a/ui/include/classes/api/services/CHostBase.php
+++ b/ui/include/classes/api/services/CHostBase.php
@@ -128,6 +128,7 @@ abstract class CHostBase extends CApiService {
 		$del_links = [];
 		$check_double_linkage = false;
 		$del_templates = [];
+		$del_links_clear = [];
 
 		foreach ($hosts as $host) {
 			if (array_key_exists('templates', $host)) {
@@ -187,13 +188,22 @@ abstract class CHostBase extends CApiService {
 					}
 				}
 			}
+
+			if (($this instanceof CHost || $this instanceof CTemplate) && array_key_exists('templates_clear', $host)) {
+				foreach ($host['templates_clear'] as $template) {
+					$del_links_clear[$template['templateid']][$host[$id_field_name]] = true;
+				}
+			}
 		}
 
 		if ($del_templates) {
-			$this->checkTriggerDependenciesOfUpdTemplates($del_templates);
 			$this->checkTriggerExpressionsOfDelTemplates($del_templates);
 		}
 
+		if ($del_links_clear) {
+			$this->checkTriggerDependenciesOfHostTriggers($del_links_clear);
+		}
+
 		if ($ins_templates) {
 			if ($this instanceof CTemplate && $db_hosts !== null) {
 				self::checkCircularLinkageNew($ins_templates, $del_links);
@@ -209,32 +219,21 @@ abstract class CHostBase extends CApiService {
 	}
 
 	/**
-	 * Check whether triggers of existing templates have not dependencies on triggers of unlinked templates on target
-	 * hosts or templates.
+	 * Check whether all templates of triggers of unlinking templates are unlinked from target hosts or templates.
 	 *
 	 * @param array $del_templates
 	 * @param array $del_templates[<templateid>][<hostid>]  Array of IDs of existing templates.
 	 *
-	 * @throws APIException
+	 * @throws APIException if not linked template is found.
 	 */
-	protected function checkTriggerDependenciesOfUpdTemplates(array $del_templates): void {
-		$all_upd_templates = [];
-
-		foreach ($del_templates as $hosts) {
-			foreach ($hosts as $hostid => $upd_templateids) {
-				$all_upd_templates += array_flip($upd_templateids);
-			}
-		}
-
+	protected function checkTriggerExpressionsOfDelTemplates(array $del_templates): void {
 		$result = DBselect(
-			'SELECT DISTINCT i.hostid AS del_templateid,td.triggerid_down,ii.hostid'.
-			' FROM items i,functions f,trigger_depends td,functions ff,items ii'.
+			'SELECT DISTINCT i.hostid AS del_templateid,f.triggerid,ii.hostid'.
+			' FROM items i,functions f,functions ff,items ii'.
 			' WHERE i.itemid=f.itemid'.
-				' AND f.triggerid=td.triggerid_up'.
-				' AND td.triggerid_down=ff.triggerid'.
+				' AND f.triggerid=ff.triggerid'.
 				' AND ff.itemid=ii.itemid'.
-				' AND '.dbConditionInt('i.hostid', array_keys($del_templates)).
-				' AND '.dbConditionInt('ii.hostid', array_keys($all_upd_templates))
+				' AND '.dbConditionInt('i.hostid', array_keys($del_templates))
 		);
 
 		while ($row = DBfetch($result)) {
@@ -248,12 +247,12 @@ abstract class CHostBase extends CApiService {
 
 					$triggers = DB::select('triggers', [
 						'output' => ['description'],
-						'triggerids' => $row['triggerid_down']
+						'triggerids' => $row['triggerid']
 					]);
 
 					$error = ($objects[$hostid]['status'] == HOST_STATUS_TEMPLATE)
-						? _('Cannot unlink template "%1$s" without template "%2$s" from template "%3$s" due to dependency of trigger "%4$s".')
-						: _('Cannot unlink template "%1$s" without template "%2$s" from host "%3$s" due to dependency of trigger "%4$s".');
+						? _('Cannot unlink template "%1$s" without template "%2$s" from template "%3$s" due to expression of trigger "%4$s".')
+						: _('Cannot unlink template "%1$s" without template "%2$s" from host "%3$s" due to expression of trigger "%4$s".');
 
 					self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $objects[$row['del_templateid']]['host'],
 						$objects[$row['hostid']]['host'], $objects[$hostid]['host'], $triggers[0]['description']
@@ -264,47 +263,165 @@ abstract class CHostBase extends CApiService {
 	}
 
 	/**
-	 * Check whether all templates of triggers of unlinking templates are unlinked from target hosts or templates.
+	 * Check whether the triggers of the target hosts or templates don't have a dependencies on the triggers of the
+	 * unlinking (with cleaning) templates.
 	 *
-	 * @param array $del_templates
-	 * @param array $del_templates[<templateid>][<hostid>]  Array of IDs of existing templates.
+	 * @param array $del_links_clear[<templateid>][<hostid>]
 	 *
-	 * @throws APIException if not linked template is found.
+	 * @throws APIException
 	 */
-	protected function checkTriggerExpressionsOfDelTemplates(array $del_templates): void {
+	protected function checkTriggerDependenciesOfHostTriggers(array $del_links_clear): void {
+		$del_host_templates = [];
+
+		foreach ($del_links_clear as $templateid => $hosts) {
+			foreach ($hosts as $hostid => $foo) {
+				$del_host_templates[$hostid][] = $templateid;
+			}
+		}
+
 		$result = DBselect(
-			'SELECT DISTINCT i.hostid AS del_templateid,f.triggerid,ii.hostid'.
-			' FROM items i,functions f,functions ff,items ii'.
+			'SELECT DISTINCT i.hostid AS templateid,t.triggerid,ii.hostid'.
+			' FROM items i,functions f,triggers t,functions ff,items ii'.
 			' WHERE i.itemid=f.itemid'.
-				' AND f.triggerid=ff.triggerid'.
+				' AND f.triggerid=t.templateid'.
+				' AND t.triggerid=ff.triggerid'.
 				' AND ff.itemid=ii.itemid'.
-				' AND '.dbConditionInt('i.hostid', array_keys($del_templates))
+				' AND '.dbConditionId('i.hostid', array_keys($del_links_clear)).
+				' AND '.dbConditionId('ii.hostid', array_keys($del_host_templates))
 		);
 
+		$trigger_links = [];
+
 		while ($row = DBfetch($result)) {
-			foreach ($del_templates[$row['del_templateid']] as $hostid => $upd_templateids) {
-				if (in_array($row['hostid'], $upd_templateids)) {
+			if (in_array($row['templateid'], $del_host_templates[$row['hostid']])) {
+				$trigger_links[$row['triggerid']][$row['hostid']] = $row['templateid'];
+			}
+		}
+
+		if (!$trigger_links) {
+			return;
+		}
+
+		$result = DBselect(
+			'SELECT DISTINCT td.triggerid_up,td.triggerid_down,i.hostid'.
+			' FROM trigger_depends td,functions f,items i'.
+			' WHERE td.triggerid_down=f.triggerid'.
+				' AND f.itemid=i.itemid'.
+				' AND '.dbConditionId('td.triggerid_up', array_keys($trigger_links)).
+				' AND '.dbConditionId('td.triggerid_down', array_keys($trigger_links), true).
+				' AND '.dbConditionId('i.hostid', array_keys($del_host_templates))
+		);
+
+		while ($row = DBfetch($result)) {
+			foreach ($trigger_links[$row['triggerid_up']] as $hostid => $templateid) {
+				if (bccomp($row['hostid'], $hostid) == 0) {
 					$objects = DB::select('hosts', [
 						'output' => ['host', 'status'],
-						'hostids' => [$row['del_templateid'], $row['hostid'], $hostid],
+						'hostids' => [$templateid, $hostid],
 						'preservekeys' => true
 					]);
 
 					$triggers = DB::select('triggers', [
 						'output' => ['description'],
-						'triggerids' => $row['triggerid']
+						'triggerids' => $row['triggerid_down']
 					]);
 
 					$error = ($objects[$hostid]['status'] == HOST_STATUS_TEMPLATE)
-						? _('Cannot unlink template "%1$s" without template "%2$s" from template "%3$s" due to expression of trigger "%4$s".')
-						: _('Cannot unlink template "%1$s" without template "%2$s" from host "%3$s" due to expression of trigger "%4$s".');
+						? _('Cannot unlink template "%1$s" from template "%2$s" due to dependency of trigger "%3$s".')
+						: _('Cannot unlink template "%1$s" from host "%2$s" due to dependency of trigger "%3$s".');
 
-					self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $objects[$row['del_templateid']]['host'],
-						$objects[$row['hostid']]['host'], $objects[$hostid]['host'], $triggers[0]['description']
+					self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $objects[$templateid]['host'],
+						$objects[$hostid]['host'], $triggers[0]['description']
 					));
 				}
 			}
 		}
+
+		if ($this instanceof CTemplate) {
+			$trigger_hosts = [];
+
+			foreach ($trigger_links as $triggerid => $hostids) {
+				$trigger_hosts[$triggerid] = array_keys($hostids);
+			}
+
+			$trigger_map = [];
+
+			while (true) {
+				$result = DBselect(
+					'SELECT DISTINCT t.templateid,t.triggerid,i.hostid'.
+					' FROM triggers t,functions f,items i'.
+					' WHERE t.triggerid=f.triggerid'.
+						' AND f.itemid=i.itemid'.
+						' AND '.dbConditionInt('t.templateid', array_keys($trigger_hosts))
+				);
+
+				$_trigger_hosts = [];
+				$hostids = [];
+
+				while ($row = DBfetch($result)) {
+					foreach ($trigger_hosts[$row['templateid']] as $hostid) {
+						if (array_key_exists($row['hostid'], $del_host_templates)
+								&& in_array($hostid, $del_host_templates[$row['hostid']])) {
+							continue;
+						}
+
+						$trigger_map[$row['triggerid']] = $row['templateid'];
+						$_trigger_hosts[$row['triggerid']][] = $row['hostid'];
+						$hostids[$row['hostid']] = true;
+					}
+				}
+
+				if (!$_trigger_hosts) {
+					break;
+				}
+
+				$trigger_hosts = $_trigger_hosts;
+
+				$result = DBselect(
+					'SELECT DISTINCT td.triggerid_up,td.triggerid_down,i.hostid'.
+					' FROM trigger_depends td,functions f,items i'.
+					' WHERE td.triggerid_down=f.triggerid'.
+						' AND f.itemid=i.itemid'.
+						' AND '.dbConditionId('td.triggerid_up', array_keys($trigger_hosts)).
+						' AND '.dbConditionId('td.triggerid_down', array_keys($trigger_hosts), true).
+						' AND '.dbConditionId('i.hostid', array_keys($hostids))
+				);
+
+				while ($row = DBfetch($result)) {
+					foreach ($trigger_hosts[$row['triggerid_up']] as $hostid) {
+						if (bccomp($row['hostid'], $hostid) == 0) {
+							$triggerid = $row['triggerid_up'];
+
+							do {
+								$triggerid = $trigger_map[$triggerid];
+							} while (array_key_exists($triggerid, $trigger_map));
+
+							$from_hostid = key($trigger_links[$triggerid]);
+							$templateid = $trigger_links[$triggerid][$from_hostid];
+
+							$objects = DB::select('hosts', [
+								'output' => ['host', 'status'],
+								'hostids' => [$templateid, $from_hostid, $hostid],
+								'preservekeys' => true
+							]);
+
+							$triggers = DB::select('triggers', [
+								'output' => ['description'],
+								'triggerids' => $row['triggerid_down']
+							]);
+
+							$error = ($objects[$hostid]['status'] == HOST_STATUS_TEMPLATE)
+								? _('Cannot unlink template "%1$s" from template "%2$s" due to dependency of trigger "%3$s" on template "%4$s".')
+								: _('Cannot unlink template "%1$s" from template "%2$s" due to dependency of trigger "%3$s" on host "%4$s".');
+
+							self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $objects[$templateid]['host'],
+								$objects[$from_hostid]['host'], $triggers[0]['description'], $objects[$hostid]['host']
+							));
+						}
+					}
+				}
+			}
+		}
 	}
 
 	/**
@@ -367,18 +484,22 @@ abstract class CHostBase extends CApiService {
 						]);
 
 						foreach ($templates as $template) {
+							$description = '"'.$template['host'].'"';
+
 							if (bccomp($template['hostid'], $templateid) == 0) {
-								$template_name = '"'.$template['host'].'"';
+								$template_name = $description;
 							}
 							else {
-								$links_path[$template['hostid']] = '"'.$template['host'].'"';
+								$links_path[$template['hostid']] = $description;
 							}
 						}
 
-						$circular_linkage = $template_name.' -> '.implode(' -> ', $links_path).' -> '.$template_name;
+						$circular_linkage = (bccomp($templateid, $hostid) == 0)
+							? $template_name.' -> '.$template_name
+							: $template_name.' -> '.implode(' -> ', $links_path).' -> '.$template_name;
 
 						self::exception(ZBX_API_ERROR_PARAMETERS, _s(
-							'Cannot link template "%1$s" to template "%2$s" because circular linkage (%3$s) will occurs.',
+							'Cannot link template "%1$s" to template "%2$s", because a circular linkage (%3$s) would occur.',
 							$templates[$templateid]['host'], $templates[$hostid]['host'], $circular_linkage
 						));
 					}
@@ -412,7 +533,10 @@ abstract class CHostBase extends CApiService {
 
 				if ($hostid_links) {
 					$links_path[$hostid] = true;
-					return self::circularLinkageExists($links, $templateid, $hostid_links, $links_path);
+
+					if (self::circularLinkageExists($links, $templateid, $hostid_links, $links_path)) {
+						return true;
+					}
 				}
 			}
 		}
@@ -511,13 +635,13 @@ abstract class CHostBase extends CApiService {
 				]);
 
 				if ($objects[$hostid]['status'] == HOST_STATUS_TEMPLATE) {
-					$error = _('Cannot link template "%1$s" to template "%2$s" because its parent template "%3$s" will be linked twice.');
+					$error = _('Cannot link template "%1$s" to template "%2$s", because its parent template "%3$s" would be linked twice.');
 				}
 				elseif ($objects[$hostid]['flags'] == ZBX_FLAG_DISCOVERY_PROTOTYPE) {
-					$error = _('Cannot link template "%1$s" to host prototype "%2$s" because its parent template "%3$s" will be linked twice.');
+					$error = _('Cannot link template "%1$s" to host prototype "%2$s", because its parent template "%3$s" would be linked twice.');
 				}
 				else {
-					$error = _('Cannot link template "%1$s" to host "%2$s" because its parent template "%3$s" will be linked twice.');
+					$error = _('Cannot link template "%1$s" to host "%2$s", because its parent template "%3$s" would be linked twice.');
 				}
 
 				self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $objects[$ins_templateid]['host'],
diff --git a/ui/include/classes/api/services/CHostGeneral.php b/ui/include/classes/api/services/CHostGeneral.php
index 8961d3b508a..1f48b1e1952 100644
--- a/ui/include/classes/api/services/CHostGeneral.php
+++ b/ui/include/classes/api/services/CHostGeneral.php
@@ -158,11 +158,13 @@ abstract class CHostGeneral extends CHostBase {
 	 * @param array  $templateids
 	 * @param array  $db_hosts
 	 */
-	protected function massCheckTemplatesLinks(string $method, array $templateids, array $db_hosts): void {
+	protected function massCheckTemplatesLinks(string $method, array $templateids, array $db_hosts,
+			array $templateids_clear = []): void {
 		$ins_templates = [];
 		$del_links = [];
 		$check_double_linkage = false;
 		$del_templates = [];
+		$del_links_clear  = [];
 
 		foreach ($db_hosts as $hostid => $db_host) {
 			$db_templateids = array_column($db_host['templates'], 'templateid');
@@ -211,14 +213,21 @@ abstract class CHostGeneral extends CHostBase {
 				if ($upd_templateids) {
 					$del_templates[$db_templateid][$hostid] = $upd_templateids;
 				}
+
+				if (array_key_exists($db_templateid, $templateids_clear)) {
+					$del_links_clear[$db_templateid][$hostid] = true;
+				}
 			}
 		}
 
 		if ($del_templates) {
-			$this->checkTriggerDependenciesOfUpdTemplates($del_templates);
 			$this->checkTriggerExpressionsOfDelTemplates($del_templates);
 		}
 
+		if ($del_links_clear) {
+			$this->checkTriggerDependenciesOfHostTriggers($del_links_clear);
+		}
+
 		if ($ins_templates) {
 			if ($this instanceof CTemplate) {
 				self::checkCircularLinkageNew($ins_templates, $del_links);
@@ -760,11 +769,7 @@ abstract class CHostGeneral extends CHostBase {
 
 		API::Graph()->syncTemplates($link_request);
 
-		API::Trigger()->syncTemplateDependencies($link_request);
-
-		if ($ruleids) {
-			API::TriggerPrototype()->syncTemplateDependencies($link_request);
-		}
+		CTriggerGeneral::syncTemplateDependencies($link_request['templateids'], $link_request['hostids']);
 	}
 
 	/**
@@ -998,8 +1003,7 @@ abstract class CHostGeneral extends CHostBase {
 		}
 
 		foreach ($link_requests as $link_request){
-			API::Trigger()->syncTemplateDependencies($link_request);
-			API::TriggerPrototype()->syncTemplateDependencies($link_request);
+			CTriggerGeneral::syncTemplateDependencies($link_request['templateids'], $link_request['hostids']);
 		}
 
 		return $hosts_linkage_inserts;
diff --git a/ui/include/classes/api/services/CTemplate.php b/ui/include/classes/api/services/CTemplate.php
index 2a5117aad1a..e08aeac8c7c 100644
--- a/ui/include/classes/api/services/CTemplate.php
+++ b/ui/include/classes/api/services/CTemplate.php
@@ -718,18 +718,36 @@ class CTemplate extends CHostGeneral {
 			' FROM hosts_templates ht,hosts_templates htt'.
 			' WHERE ht.hostid=htt.hostid'.
 				' AND ht.templateid!=htt.templateid'.
-				' AND '.dbConditionInt('ht.templateid', $templateids).
-				' AND '.dbConditionInt('htt.templateid', $templateids, true)
+				' AND '.dbConditionId('ht.templateid', $templateids).
+				' AND '.dbConditionId('htt.templateid', $templateids, true)
 		);
 
 		while ($row = DBfetch($result)) {
 			$del_templates[$row['del_templateid']][$row['hostid']][] = $row['templateid'];
 		}
 
+		$del_links_clear = [];
+		$options = [
+			'output' => ['templateid', 'hostid'],
+			'filter' => [
+				'templateid' => $templateids
+			]
+		];
+		$result = DBselect(DB::makeSql('hosts_templates', $options));
+
+		while ($row = DBfetch($result)) {
+			if (!in_array($row['hostid'], $templateids)) {
+				$del_links_clear[$row['templateid']][$row['hostid']] = true;
+			}
+		}
+
 		if ($del_templates) {
-			$this->checkTriggerDependenciesOfUpdTemplates($del_templates);
 			$this->checkTriggerExpressionsOfDelTemplates($del_templates);
 		}
+
+		if ($del_links_clear) {
+			$this->checkTriggerDependenciesOfHostTriggers($del_links_clear);
+		}
 	}
 
 	/**
@@ -1057,10 +1075,10 @@ class CTemplate extends CHostGeneral {
 				}
 
 				if (array_key_exists('templates_link', $data)) {
-					$this->massCheckTemplatesLinks('massupdate', $templateids_link, $db_templates);
+					$this->massCheckTemplatesLinks('massupdate', $templateids_link, $db_templates, $templateids_clear);
 				}
 				else {
-					$this->massCheckTemplatesLinks('massremove', $templateids_clear, $db_templates);
+					$this->massCheckTemplatesLinks('massremove', $templateids_clear, $db_templates, $templateids_clear);
 				}
 			}
 		}
@@ -1144,7 +1162,9 @@ class CTemplate extends CHostGeneral {
 
 			$this->massAddAffectedObjects('templates', $templateids, $db_templates);
 
-			$this->massCheckTemplatesLinks('massremove', $templateids, $db_templates);
+			$this->massCheckTemplatesLinks('massremove', $templateids, $db_templates,
+				array_key_exists('templateids_clear', $data) ? $data['templateids_clear'] : []
+			);
 		}
 	}
 
diff --git a/ui/include/classes/api/services/CTrigger.php b/ui/include/classes/api/services/CTrigger.php
index 50c5b972f1e..db00f0c359a 100644
--- a/ui/include/classes/api/services/CTrigger.php
+++ b/ui/include/classes/api/services/CTrigger.php
@@ -524,29 +524,15 @@ class CTrigger extends CTriggerGeneral {
 	 */
 	public function create(array $triggers) {
 		$this->validateCreate($triggers);
+
 		$this->createReal($triggers);
+		$this->checkDependenciesLinks($triggers);
+
 		$this->inherit($triggers);
 
-		// Clear all dependencies on inherited triggers.
-		$this->deleteDependencies($triggers);
+		$this->updateDependencies($triggers);
 
-		// Add new dependencies.
-		foreach ($triggers as $trigger) {
-			if (!array_key_exists('dependencies', $trigger) || !$trigger['dependencies']) {
-				continue;
-			}
-
-			$new_dependencies = [];
-			foreach ($trigger['dependencies'] as $dependency) {
-				$new_dependencies[] = [
-					'triggerid' => $trigger['triggerid'],
-					'dependsOnTriggerid' => $dependency['triggerid']
-				];
-			}
-			$this->addDependencies($new_dependencies);
-		}
-
-		return ['triggerids' => zbx_objectValues($triggers, 'triggerid')];
+		return ['triggerids' => array_column($triggers, 'triggerid')];
 	}
 
 	/**
@@ -558,51 +544,17 @@ class CTrigger extends CTriggerGeneral {
 	 *
 	 * @return array
 	 */
-	public function update(array $triggers) {
+	public function update(array $triggers): array {
 		$this->validateUpdate($triggers, $db_triggers);
 
-		$validate_dependencies = [];
-		foreach ($triggers as $tnum => $trigger) {
-			$db_trigger = $db_triggers[$tnum];
-
-			$expressions_changed = ($trigger['expression'] !== $db_trigger['expression']
-					|| $trigger['recovery_expression'] !== $db_trigger['recovery_expression']);
-
-			if ($expressions_changed && $db_trigger['dependencies'] && !array_key_exists('dependencies', $trigger)) {
-				$validate_dependencies[] = [
-					'triggerid' => $trigger['triggerid'],
-					'dependencies' => zbx_objectValues($db_trigger['dependencies'], 'triggerid')
-				];
-			}
-		}
-
-		if ($validate_dependencies) {
-			$this->checkDependencies($validate_dependencies);
-			$this->checkDependencyParents($validate_dependencies);
-		}
-
 		$this->updateReal($triggers, $db_triggers);
+		self::checkExistingDependencies($triggers, $db_triggers);
+
 		$this->inherit($triggers);
 
-		foreach ($triggers as $trigger) {
-			// Replace dependencies.
-			if (array_key_exists('dependencies', $trigger)) {
-				$this->deleteDependencies($trigger);
-
-				if ($trigger['dependencies']) {
-					$new_dependencies = [];
-					foreach ($trigger['dependencies'] as $dependency) {
-						$new_dependencies[] = [
-							'triggerid' => $trigger['triggerid'],
-							'dependsOnTriggerid' => $dependency['triggerid']
-						];
-					}
-					$this->addDependencies($new_dependencies);
-				}
-			}
-		}
+		$this->updateDependencies($triggers, $db_triggers);
 
-		return ['triggerids' => zbx_objectValues($triggers, 'triggerid')];
+		return ['triggerids' => array_column($triggers, 'triggerid')];
 	}
 
 	/**
@@ -663,498 +615,235 @@ class CTrigger extends CTriggerGeneral {
 	}
 
 	/**
-	 * Validates the input for the addDependencies() method.
-	 *
-	 * @param array $triggers_data
-	 * @param bool  $inherited
+	 * Check the existing dependencies if the trigger expressions were changed.
 	 *
-	 * @throws APIException if the given dependencies are invalid.
+	 * @param array $triggers
+	 * @param array $db_triggers
 	 */
-	protected function validateAddDependencies(array &$triggers_data, $inherited = false) {
-		$api_input_rules = ['type' => API_OBJECTS, 'flags' => API_NOT_EMPTY | API_NORMALIZE, 'uniq' => [['triggerid', 'dependsOnTriggerid']], 'fields' => [
-			'triggerid' =>			['type' => API_ID, 'flags' => API_REQUIRED],
-			'dependsOnTriggerid' =>	['type' => API_ID, 'flags' => API_REQUIRED]
-		]];
-		if (!CApiInputValidator::validate($api_input_rules, $triggers_data, '/', $error)) {
-			self::exception(ZBX_API_ERROR_PARAMETERS, $error);
-		}
+	private static function checkExistingDependencies(array $triggers, array $db_triggers): void {
+		$triggerids = [];
+		$hostids = [];
 
-		$triggerids = zbx_objectValues($triggers_data, 'triggerid');
-		$triggerids = array_keys(array_flip($triggerids));
+		foreach ($triggers as $trigger) {
+			if (array_key_exists('hosts', $db_triggers[$trigger['triggerid']])) {
+				$triggerids[$trigger['triggerid']] = true;
+				$hostids += $db_triggers[$trigger['triggerid']]['hosts'];
+			}
+		}
 
-		$permission_check = $inherited
-			? ['nopermissions' => true]
-			: ['editable' => true];
+		if (!$triggerids) {
+			return;
+		}
 
-		$triggers = $this->get([
-			'output' => ['triggerid', 'description', 'templateid', 'flags'],
-			'triggerids' => $triggerids,
-			'preservekeys' => true
-		] + $permission_check);
+		/*
+		 * It's necessary to perform the check of existing dependencies only if, as the result of the expression change,
+		 * the trigger no longer belongs to any of the previous hosts.
+		 */
+		$result = DBselect(
+			'SELECT DISTINCT f.triggerid,i.hostid'.
+			' FROM functions f,items i'.
+			' WHERE f.itemid=i.itemid'.
+				' AND '.dbConditionId('f.triggerid', array_keys($triggerids)).
+				' AND '.dbConditionId('i.hostid', array_keys($hostids))
+		);
 
-		if (count($triggerids) != count($triggers)) {
-			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
+		while ($row = DBfetch($result)) {
+			if (array_key_exists($row['hostid'], $db_triggers[$row['triggerid']]['hosts'])) {
+				unset($db_triggers[$row['triggerid']]['hosts'][$row['hostid']]);
+			}
 		}
 
+		$trigger_dependencies = [];
+
 		foreach ($triggers as $trigger) {
-			if ($trigger['templateid'] && !$inherited) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS, _s('Cannot update dependencies of inherited trigger "%1$s".',
-					$trigger['description']
-				));
+			if (!array_key_exists($trigger['triggerid'], $triggerids)
+					|| !$db_triggers[$trigger['triggerid']]['hosts']) {
+				continue;
 			}
 
-			if ($trigger['flags'] == ZBX_FLAG_DISCOVERY_CREATED) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS, _s('Cannot update "%2$s" for a discovered trigger "%1$s".',
-					$trigger['description'], 'dependencies'
-				));
+			$dependencies = array_key_exists('dependencies', $trigger)
+				? $trigger['dependencies']
+				: $db_triggers[$trigger['triggerid']]['dependencies'];
+
+			foreach ($dependencies as $trigger_up) {
+				$trigger_dependencies[$trigger_up['triggerid']][$trigger['triggerid']] = true;
 			}
 		}
 
-		$dep_triggerids = [];
-		$triggers = [];
-		foreach ($triggers_data as $dep) {
-			$triggerid = $dep['triggerid'];
-
-			if (!array_key_exists($dep['triggerid'], $triggers)) {
-				$triggers[$triggerid] = [
-					'triggerid' => $triggerid,
-					'dependencies' => []
-				];
-			}
-			$triggers[$triggerid]['dependencies'][] = $dep['dependsOnTriggerid'];
-			$dep_triggerids[$dep['dependsOnTriggerid']] = $dep['dependsOnTriggerid'];
+		if (!$trigger_dependencies) {
+			return;
 		}
 
-		if (!$inherited) {
-			$count = $this->get([
-				'countOutput' => true,
-				'triggerids' => $dep_triggerids
-			]);
+		/*
+		 * There is no need to perform a check for dependency duplicates, because we are checking for existing
+		 * dependencies that cannot have them. Also there is no need to perform the check on circular
+		 * dependencies, because the dependencies are based on trigger IDs. Even if the expressions have changed, the
+		 * trigger IDs remain the same.
+		 */
 
-			if ($count != count($dep_triggerids)) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS,
-					_('No permissions to referred object or it does not exist!')
-				);
-			}
-		}
+		$trigger_hosts = self::getTriggerHosts($trigger_dependencies);
 
-		$this->checkDependencies($triggers);
-		$this->checkDependencyParents($triggers);
-		$this->checkDependencyDuplicates($triggers);
+		/*
+		 * The template trigger can become a host trigger. Therefore the template trigger dependencies may remain
+		 * after the update.
+		 */
+		self::checkDependenciesOfHostTriggers($trigger_dependencies, $trigger_hosts);
+
+		/*
+		 * The template (or host) trigger can become a trigger of another template. If after the update
+		 * the trigger became owned by another template and it also has a dependency on a trigger from another
+		 * template remaining, then we should check that:
+		 *  - Such dependency did not become a dependency on a trigger from the parent template.
+		 *  - Such dependency did not become a dependency on a trigger from the child template or host.
+		 *  - The template of the trigger-up is linked to all child templates of the new trigger's template.
+		 */
+		self::checkDependenciesOfTemplateTriggers($trigger_dependencies, $trigger_hosts);
 	}
 
 	/**
-	 * Add the given dependencies and inherit them on all child triggers.
+	 * Validates the input for the addDependencies() method.
 	 *
-	 * @param array $triggers_data  An array of trigger dependency pairs, each pair in the form of
-	 *                              ['triggerid' => 1, 'dependsOnTriggerid' => 2].
-	 * @param bool  $inherited      Determines either to check permissions for added dependencies. Permissions are not
-	 *                              validated for inherited triggers.
+	 * @param array      $triggers_data
+	 * @param array|null $triggers
+	 * @param array|null $db_triggers
 	 *
-	 * @return array
+	 * @throws APIException if the given dependencies are invalid.
 	 */
-	public function addDependencies(array $triggers_data, $inherited = false) {
-		$this->validateAddDependencies($triggers_data, $inherited);
-
-		foreach ($triggers_data as $dep) {
-			$triggerId = $dep['triggerid'];
-			$depTriggerId = $dep['dependsOnTriggerid'];
-
-			DB::insert('trigger_depends', [[
-				'triggerid_down' => $triggerId,
-				'triggerid_up' => $depTriggerId
-			]]);
-
-			// propagate the dependencies to the child triggers
-			$childTriggers = API::getApiService()->select($this->tableName(), [
-				'output' => ['triggerid'],
-				'filter' => [
-					'templateid' => $triggerId
-				]
-			]);
-			if ($childTriggers) {
-				foreach ($childTriggers as $childTrigger) {
-					$childHostsQuery = get_hosts_by_triggerid($childTrigger['triggerid']);
-					while ($childHost = DBfetch($childHostsQuery)) {
-						$newDep = [$childTrigger['triggerid'] => $depTriggerId];
-						$newDep = replace_template_dependencies($newDep, $childHost['hostid']);
-
-						$this->addDependencies([[
-							'triggerid' => $childTrigger['triggerid'],
-							'dependsOnTriggerid' => $newDep[$childTrigger['triggerid']]
-						]], true);
-					}
-				}
-			}
+	protected function validateAddDependencies(array $triggers_data, ?array &$triggers, ?array &$db_triggers): void {
+		$api_input_rules = ['type' => API_OBJECTS, 'flags' => API_NOT_EMPTY | API_NORMALIZE, 'uniq' => [['triggerid', 'dependsOnTriggerid']], 'fields' => [
+			'triggerid' =>			['type' => API_ID, 'flags' => API_REQUIRED],
+			'dependsOnTriggerid' =>	['type' => API_ID, 'flags' => API_REQUIRED]
+		]];
+
+		if (!CApiInputValidator::validate($api_input_rules, $triggers_data, '/', $error)) {
+			self::exception(ZBX_API_ERROR_PARAMETERS, $error);
 		}
 
-		return ['triggerids' => array_unique(zbx_objectValues($triggers_data, 'triggerid'))];
-	}
+		$triggers = [];
+		$trigger_dependencies = [];
 
-	/**
-	 * Validates the input for the deleteDependencies() method.
-	 *
-	 * @param array $triggers
-	 * @param bool  $inherited
-	 *
-	 * @throws APIException if the given input is invalid
-	 */
-	protected function validateDeleteDependencies(array $triggers, $inherited) {
-		if (!$triggers) {
-			self::exception(ZBX_API_ERROR_PARAMETERS, _('Empty input parameter.'));
-		}
+		foreach ($triggers_data as $dependency) {
+			$triggers[$dependency['triggerid']]['triggerid'] = $dependency['triggerid'];
+			$triggers[$dependency['triggerid']]['dependencies'][] = ['triggerid' => $dependency['dependsOnTriggerid']];
 
-		foreach ($triggers as $trigger) {
-			if (!check_db_fields(['triggerid' => null], $trigger)) {
-				self::exception(ZBX_API_ERROR_PARAMETERS, _('Incorrect input parameters.'));
-			}
+			$trigger_dependencies[$dependency['dependsOnTriggerid']][$dependency['triggerid']] = true;
 		}
 
-		$triggerids = zbx_objectValues($triggers, 'triggerid');
-		$triggerids = array_keys(array_flip($triggerids));
+		$triggers = array_values($triggers);
 
-		$permission_check = $inherited
-			? ['nopermissions' => true]
-			: ['editable' => true];
-
-		$triggers = $this->get([
-			'output' => ['triggerid', 'description', 'templateid', 'flags'],
-			'triggerids' => $triggerids,
+		$db_triggers = $this->get([
+			'output' => ['triggerid', 'description', 'flags'],
+			'triggerids' => array_column($triggers, 'triggerid'),
+			'editable' => true,
 			'preservekeys' => true
-		] + $permission_check);
+		]);
 
-		foreach ($triggerids as $triggerid) {
-			if (!array_key_exists($triggerid, $triggers)) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS,
-					_('No permissions to referred object or it does not exist!')
-				);
-			}
+		if (count($db_triggers) != count($triggers)) {
+			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
 		}
 
-		foreach ($triggers as $trigger) {
-			if ($trigger['templateid'] && !$inherited) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS, _s('Cannot update dependencies of inherited trigger "%1$s".',
-					$trigger['description']
-				));
-			}
-
-			if ($trigger['flags'] == ZBX_FLAG_DISCOVERY_CREATED) {
+		foreach ($db_triggers as $db_trigger) {
+			if ($db_trigger['flags'] == ZBX_FLAG_DISCOVERY_CREATED) {
 				self::exception(ZBX_API_ERROR_PERMISSIONS, _s('Cannot update "%2$s" for a discovered trigger "%1$s".',
-					$trigger['description'], 'dependencies'
+					$db_trigger['description'], 'dependencies'
 				));
 			}
 		}
-	}
 
-	/**
-	 * Deletes all trigger dependencies from the given triggers and their children.
-	 *
-	 * @param array $triggers   an array of triggers with the 'triggerid' field defined
-	 * @param bool  $inherited  Determines either to check permissions for deleted dependencies. Permissions are not
-	 *                          validated for inherited triggers.
-	 *
-	 * @return array
-	 */
-	public function deleteDependencies(array $triggers, $inherited = false) {
-		$triggers = zbx_toArray($triggers);
+		$count = $this->get([
+			'countOutput' => true,
+			'triggerids' => array_keys($trigger_dependencies)
+		]);
 
-		$this->validateDeleteDependencies($triggers, $inherited);
+		if ($count != count($trigger_dependencies)) {
+			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
+		}
 
-		$triggerids = zbx_objectValues($triggers, 'triggerid');
+		self::checkDependencyDuplicates($trigger_dependencies);
+		self::checkCircularDependencies($trigger_dependencies);
 
-		try {
-			// delete the dependencies from the child triggers
-			$childTriggers = DB::select($this->tableName(), [
-				'output' => ['triggerid'],
-				'filter' => [
-					'templateid' => $triggerids
-				]
-			]);
-			if ($childTriggers) {
-				$this->deleteDependencies($childTriggers, true);
-			}
+		$trigger_hosts = self::getTriggerHosts($trigger_dependencies);
 
-			DB::delete('trigger_depends', [
-				'triggerid_down' => $triggerids
-			]);
-		}
-		catch (APIException $e) {
-			self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot delete dependency'));
-		}
+		self::checkDependenciesOfHostTriggers($trigger_dependencies, $trigger_hosts);
+		self::checkDependenciesOfTemplateTriggers($trigger_dependencies, $trigger_hosts);
 
-		return ['triggerids' => $triggerids];
+		foreach ($db_triggers as &$db_trigger) {
+			$db_trigger['dependencies'] = [];
+		}
+		unset($db_trigger);
 	}
 
 	/**
-	 * Synchronizes the templated trigger dependencies on the given hosts inherited from the given
-	 * templates.
-	 * Update dependencies, do it after all triggers that can be dependent were created/updated on
-	 * all child hosts/templates. Starting from highest level template triggers select triggers from
-	 * one level lower, then for each lower trigger look if it's parent has dependencies, if so
-	 * find this dependency trigger child on dependent trigger host and add new dependency.
+	 * Add the given dependencies and inherit them on all child triggers.
 	 *
-	 * @param array $data
+	 * @param array $triggers_data  An array of trigger dependency pairs, each pair in the form of
+	 *                              ['triggerid' => 1, 'dependsOnTriggerid' => 2].
+	 *
+	 * @return array
 	 */
-	public function syncTemplateDependencies(array $data) {
-		$templateIds = zbx_toArray($data['templateids']);
-		$hostIds = zbx_toArray($data['hostids']);
-
-		$parentTriggers = $this->get([
-			'output' => ['triggerid'],
-			'selectDependencies' => ['triggerid'],
-			'hostids' => $templateIds,
-			'preservekeys' => true,
-			'nopermissions' => true
-		]);
-
-		if ($parentTriggers) {
-			$childTriggers = $this->get([
-				'output' => ['triggerid', 'templateid'],
-				'hostids' => ($hostIds) ? $hostIds : null,
-				'filter' => ['templateid' => array_keys($parentTriggers)],
-				'nopermissions' => true,
-				'preservekeys' => true,
-				'selectHosts' => ['hostid']
-			]);
+	public function addDependencies(array $triggers_data) {
+		$this->validateAddDependencies($triggers_data, $triggers, $db_triggers);
 
-			if ($childTriggers) {
-				$newDependencies = [];
-				foreach ($childTriggers as $childTrigger) {
-					$parentDependencies = $parentTriggers[$childTrigger['templateid']]['dependencies'];
-					if ($parentDependencies) {
-						$dependencies = [];
-						foreach ($parentDependencies as $depTrigger) {
-							$dependencies[] = $depTrigger['triggerid'];
-						}
-						$host = reset($childTrigger['hosts']);
-						$dependencies = replace_template_dependencies($dependencies, $host['hostid']);
-						foreach ($dependencies as $depTriggerId) {
-							$newDependencies[] = [
-								'triggerid' => $childTrigger['triggerid'],
-								'dependsOnTriggerid' => $depTriggerId
-							];
-						}
-					}
-				}
-				$this->deleteDependencies($childTriggers, true);
+		self::updateDependencies($triggers, $db_triggers);
 
-				if ($newDependencies) {
-					$this->addDependencies($newDependencies, true);
-				}
-			}
-		}
+		return ['triggerids' => array_column($triggers, 'triggerid')];
 	}
 
 	/**
-	 * Validates the dependencies of the given triggers.
+	 * @param array      $triggers
+	 * @param array|null $db_triggers
 	 *
-	 * @param array $triggers list of triggers and corresponding dependencies
-	 * @param int $triggers[]['triggerid'] trigger id
-	 * @param array $triggers[]['dependencies'] list of trigger ids on which depends given trigger
-	 *
-	 * @trows APIException if any of the dependencies is invalid
+	 * @throws APIException if the given input is invalid
 	 */
-	protected function checkDependencies(array $triggers) {
-		foreach ($triggers as $trigger) {
-			if (empty($trigger['dependencies'])) {
-				continue;
-			}
-
-			// trigger templates
-			$triggerTemplates = API::Template()->get([
-				'output' => ['status', 'hostid'],
-				'triggerids' => $trigger['triggerid'],
-				'nopermissions' => true
-			]);
-
-			// forbid dependencies from hosts to templates
-			if (!$triggerTemplates) {
-				$triggerDependencyTemplates = API::Template()->get([
-					'output' => ['templateid'],
-					'triggerids' => $trigger['dependencies'],
-					'nopermissions' => true,
-					'limit' => 1
-				]);
-				if ($triggerDependencyTemplates) {
-					self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot add dependency from a host to a template.'));
-				}
-			}
-
-			// the trigger can't depend on itself
-			if (in_array($trigger['triggerid'], $trigger['dependencies'])) {
-				self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot create dependency on trigger itself.'));
-			}
-
-			// check circular dependency
-			$downTriggerIds = [$trigger['triggerid']];
-			do {
-				// triggerid_down depends on triggerid_up
-				$res = DBselect(
-					'SELECT td.triggerid_up'.
-					' FROM trigger_depends td'.
-					' WHERE '.dbConditionInt('td.triggerid_down', $downTriggerIds)
-				);
-
-				// combine db dependencies with those to be added
-				$upTriggersIds = [];
-				while ($row = DBfetch($res)) {
-					$upTriggersIds[] = $row['triggerid_up'];
-				}
-				foreach ($downTriggerIds as $id) {
-					if (isset($triggers[$id]) && isset($triggers[$id]['dependencies'])) {
-						$upTriggersIds = array_merge($upTriggersIds, $triggers[$id]['dependencies']);
-					}
-				}
+	private function validateDeleteDependencies(array &$triggers, ?array &$db_triggers): void {
+		$api_input_rules = ['type' => API_OBJECTS, 'flags' => API_NOT_EMPTY | API_NORMALIZE, 'uniq' => [['triggerid']], 'fields' => [
+			'triggerid' =>	['type' => API_ID, 'flags' => API_REQUIRED]
+		]];
 
-				// if found trigger id is in dependent triggerids, there is a dependency loop
-				$downTriggerIds = [];
-				foreach ($upTriggersIds as $id) {
-					if (bccomp($id, $trigger['triggerid']) == 0) {
-						self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot create circular dependencies.'));
-					}
-					$downTriggerIds[] = $id;
-				}
-			} while (!empty($downTriggerIds));
+		if (!CApiInputValidator::validate($api_input_rules, $triggers, '/', $error)) {
+			self::exception(ZBX_API_ERROR_PARAMETERS, $error);
+		}
 
-			// fetch all templates that are used in dependencies
-			$triggerDependencyTemplates = API::Template()->get([
-				'output' => ['templateid'],
-				'triggerids' => $trigger['dependencies'],
-				'nopermissions' => true
-			]);
-			$depTemplateIds = zbx_toHash(zbx_objectValues($triggerDependencyTemplates, 'templateid'));
-
-			// run the check only if a templated trigger has dependencies on other templates
-			$triggerTemplateIds = zbx_toHash(zbx_objectValues($triggerTemplates, 'templateid'));
-			$tdiff = array_diff($depTemplateIds, $triggerTemplateIds);
-			if (!empty($triggerTemplateIds) && !empty($depTemplateIds) && !empty($tdiff)) {
-				$affectedTemplateIds = zbx_array_merge($triggerTemplateIds, $depTemplateIds);
-
-				// create a list of all hosts, that are children of the affected templates
-				$dbLowlvltpl = DBselect(
-					'SELECT DISTINCT ht.templateid,ht.hostid,h.host'.
-					' FROM hosts_templates ht,hosts h'.
-					' WHERE h.hostid=ht.hostid'.
-						' AND '.dbConditionInt('ht.templateid', $affectedTemplateIds)
-				);
-				$map = [];
-				while ($lowlvltpl = DBfetch($dbLowlvltpl)) {
-					if (!isset($map[$lowlvltpl['hostid']])) {
-						$map[$lowlvltpl['hostid']] = [];
-					}
-					$map[$lowlvltpl['hostid']][$lowlvltpl['templateid']] = $lowlvltpl['host'];
-				}
+		$db_triggers = $this->get([
+			'output' => ['description', 'flags'],
+			'triggerids' => array_column($triggers, 'triggerid'),
+			'editable' => true,
+			'preservekeys' => true
+		]);
 
-				// check that if some host is linked to the template, that the trigger belongs to,
-				// the host must also be linked to all of the templates, that trigger dependencies point to
-				foreach ($map as $templates) {
-					foreach ($triggerTemplateIds as $triggerTemplateId) {
-						// is the host linked to one of the trigger templates?
-						if (isset($templates[$triggerTemplateId])) {
-							// then make sure all of the dependency templates are also linked
-							foreach ($depTemplateIds as $depTemplateId) {
-								if (!isset($templates[$depTemplateId])) {
-									self::exception(ZBX_API_ERROR_PARAMETERS,
-										_s('Not all templates are linked to "%1$s".', reset($templates))
-									);
-								}
-							}
-							break;
-						}
-					}
-				}
-			}
+		if (count($db_triggers) != count($triggers)) {
+			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
 		}
-	}
 
-	/**
-	 * Check that none of the triggers have dependencies on their children. Checks only one level of inheritance, but
-	 * since it is called on each inheritance step, also works for multiple inheritance levels.
-	 *
-	 * @throws APIException     if at least one trigger is dependent on its child
-	 *
-	 * @param array $triggers
-	 */
-	protected function checkDependencyParents(array $triggers) {
-		// fetch all templated dependency trigger parents
-		$depTriggerIds = [];
-		foreach ($triggers as $trigger) {
-			foreach ($trigger['dependencies'] as $depTriggerId) {
-				$depTriggerIds[$depTriggerId] = $depTriggerId;
+		foreach ($db_triggers as $db_trigger) {
+			if ($db_trigger['flags'] == ZBX_FLAG_DISCOVERY_CREATED) {
+				self::exception(ZBX_API_ERROR_PERMISSIONS, _s('Cannot update "%2$s" for a discovered trigger "%1$s".',
+					$db_trigger['description'], 'dependencies'
+				));
 			}
 		}
-		$parentDepTriggers = DBfetchArray(DBSelect(
-			'SELECT templateid,triggerid'.
-			' FROM triggers'.
-			' WHERE templateid>0'.
-				' AND '.dbConditionInt('triggerid', $depTriggerIds)
-		));
-		if ($parentDepTriggers) {
-			$parentDepTriggers = zbx_toHash($parentDepTriggers, 'triggerid');
-			foreach ($triggers as $trigger) {
-				foreach ($trigger['dependencies'] as $depTriggerId) {
-					// check if the current trigger is the parent of the dependency trigger
-					if (isset($parentDepTriggers[$depTriggerId])
-							&& $parentDepTriggers[$depTriggerId]['templateid'] == $trigger['triggerid']) {
-
-						self::exception(ZBX_API_ERROR_PARAMETERS,
-							_s('Trigger cannot be dependent on a trigger that is inherited from it.')
-						);
-					}
-				}
-			}
+
+		foreach ($triggers as &$trigger) {
+			$trigger['dependencies'] = [];
 		}
+		unset($trigger);
+
+		self::addAffectedDependencies($triggers, $db_triggers);
 	}
 
 	/**
-	 * Checks if the given dependencies contain duplicates.
+	 * Deletes all trigger dependencies from the given triggers and their children.
 	 *
-	 * @throws APIException if the given dependencies contain duplicates
+	 * @param array $triggers An array of triggers with the 'triggerid' field defined.
 	 *
-	 * @param array $triggers
+	 * @return array
 	 */
-	protected function checkDependencyDuplicates(array $triggers) {
-		// check duplicates in array
-		$uniqueTriggers = [];
-		$duplicateTriggerId = null;
-		foreach ($triggers as $trigger) {
-			foreach ($trigger['dependencies'] as $dep) {
-				if (isset($uniqueTriggers[$trigger['triggerid']][$dep])) {
-					$duplicateTriggerId = $trigger['triggerid'];
-					break 2;
-				}
-				else {
-					$uniqueTriggers[$trigger['triggerid']][$dep] = 1;
-				}
-			}
-		}
+	public function deleteDependencies(array $triggers) {
+		$this->validateDeleteDependencies($triggers, $db_triggers);
 
-		if ($duplicateTriggerId === null) {
-			// check if dependency already exists in DB
-			foreach ($triggers as $trigger) {
-				$dbUpTriggers = DBselect(
-					'SELECT td.triggerid_up'.
-					' FROM trigger_depends td'.
-					' WHERE '.dbConditionInt('td.triggerid_up', $trigger['dependencies']).
-					' AND td.triggerid_down='.zbx_dbstr($trigger['triggerid'])
-				, 1);
-				if (DBfetch($dbUpTriggers)) {
-					$duplicateTriggerId = $trigger['triggerid'];
-					break;
-				}
-			}
-		}
+		self::updateDependencies($triggers, $db_triggers);
 
-		if ($duplicateTriggerId) {
-			$dplTrigger = DBfetch(DBselect(
-				'SELECT t.description'.
-				' FROM triggers t'.
-				' WHERE t.triggerid='.zbx_dbstr($duplicateTriggerId)
-			));
-			self::exception(ZBX_API_ERROR_PARAMETERS,
-				_s('Duplicate dependencies in trigger "%1$s".', $dplTrigger['description'])
-			);
-		}
+		return ['triggerids' => array_column($triggers, 'triggerid')];
 	}
 
 	protected function applyQueryOutputOptions($tableName, $tableAlias, array $options, array $sqlParts) {
diff --git a/ui/include/classes/api/services/CTriggerGeneral.php b/ui/include/classes/api/services/CTriggerGeneral.php
index 0a17831081b..1c01099ed24 100644
--- a/ui/include/classes/api/services/CTriggerGeneral.php
+++ b/ui/include/classes/api/services/CTriggerGeneral.php
@@ -203,7 +203,7 @@ abstract class CTriggerGeneral extends CApiService {
 							'triggerid' => $chd_trigger['triggerid'],
 							'templateid' => $tpl_trigger['triggerid']
 						];
-						$db_triggers[] = $chd_trigger;
+						$db_triggers[$chd_trigger['triggerid']] = $chd_trigger;
 						$triggerids[] = $chd_trigger['triggerid'];
 
 						$check_duplicates = ($chd_trigger['description'] !== $new_trigger['description']
@@ -247,11 +247,12 @@ abstract class CTriggerGeneral extends CApiService {
 				];
 			}
 
-			foreach ($db_triggers as $tnum => $db_trigger) {
-				$db_triggers[$tnum]['tags'] = array_key_exists($db_trigger['triggerid'], $trigger_tags)
+			foreach ($db_triggers as &$db_trigger) {
+				$db_trigger['tags'] = array_key_exists($db_trigger['triggerid'], $trigger_tags)
 					? $trigger_tags[$db_trigger['triggerid']]
 					: [];
 			}
+			unset($db_trigger);
 
 			// Add discovery rule IDs.
 			if ($this instanceof CTriggerPrototype) {
@@ -268,9 +269,10 @@ abstract class CTriggerGeneral extends CApiService {
 					$drule_by_triggerid[$row['triggerid']] = $row['parent_itemid'];
 				}
 
-				foreach ($db_triggers as $tnum => $db_trigger) {
-					$db_triggers[$tnum]['discoveryRule']['itemid'] = $drule_by_triggerid[$db_trigger['triggerid']];
+				foreach ($db_triggers as &$db_trigger) {
+					$db_trigger['discoveryRule']['itemid'] = $drule_by_triggerid[$db_trigger['triggerid']];
 				}
+				unset($db_trigger);
 			}
 		}
 
@@ -508,9 +510,9 @@ abstract class CTriggerGeneral extends CApiService {
 	}
 
 	/**
-	 * Updates the children of the triggers on the given hosts and propagates the inheritance to all child hosts.
-	 * If the given triggers was assigned to a different template or a host, all of the child triggers, that became
-	 * obsolete will be deleted.
+	 * Updates children of triggers on the given hosts and propagates the inheritance to all child hosts.
+	 * All of the child triggers that became obsolete will be deleted if the given triggers were assigned to a different
+	 * template or host.
 	 *
 	 * @param array  $triggers
 	 * @param string $triggers[]['triggerid']
@@ -914,6 +916,7 @@ abstract class CTriggerGeneral extends CApiService {
 		$descriptions = $this->populateHostIds($descriptions);
 		$this->checkAndAddUuid($triggers, $descriptions);
 		$this->checkDuplicates($descriptions);
+		$this->checkDependencies($triggers);
 	}
 
 	/**
@@ -963,8 +966,6 @@ abstract class CTriggerGeneral extends CApiService {
 	 * @throws APIException if validation failed.
 	 */
 	protected function validateUpdate(array &$triggers, array &$db_triggers = null) {
-		$db_triggers = [];
-
 		$api_input_rules = ['type' => API_OBJECTS, 'flags' => API_NOT_EMPTY | API_NORMALIZE, 'uniq' => [['description', 'expression']], 'fields' => [
 			'triggerid' =>				['type' => API_ID, 'flags' => API_REQUIRED],
 			'description' =>			['type' => API_STRING_UTF8, 'flags' => API_NOT_EMPTY, 'length' => DB::getFieldLength('triggers', 'description')],
@@ -1005,7 +1006,6 @@ abstract class CTriggerGeneral extends CApiService {
 				'templateid', 'recovery_mode', 'recovery_expression', 'correlation_mode', 'correlation_tag',
 				'manual_close', 'opdata', 'event_name'
 			],
-			'selectDependencies' => ['triggerid'],
 			'triggerids' => zbx_objectValues($triggers, 'triggerid'),
 			'editable' => true,
 			'preservekeys' => true
@@ -1035,21 +1035,17 @@ abstract class CTriggerGeneral extends CApiService {
 				self::exception(ZBX_API_ERROR_INTERNAL, _('Internal error.'));
 		}
 
-		$_db_triggers = CMacrosResolverHelper::resolveTriggerExpressions($this->get($options),
-			['sources' => ['expression', 'recovery_expression']]
-		);
+		$db_triggers = $this->get($options);
 
-		$db_trigger_tags = $_db_triggers
-			? DB::select('trigger_tag', [
-				'output' => ['triggertagid', 'triggerid', 'tag', 'value'],
-				'filter' => ['triggerid' => array_keys($_db_triggers)],
-				'preservekeys' => true
-			])
-			: [];
+		if (count($db_triggers) != count($triggers)) {
+			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
+		}
+
+		$db_triggers = CMacrosResolverHelper::resolveTriggerExpressions($db_triggers, [
+			'sources' => ['expression', 'recovery_expression']
+		]);
 
-		$_db_triggers = $this
-			->createRelationMap($db_trigger_tags, 'triggerid', 'triggertagid')
-			->mapMany($_db_triggers, $db_trigger_tags, 'tags');
+		$this->addAffectedObjects($triggers, $db_triggers);
 
 		$read_only_fields = ['description', 'expression', 'recovery_mode', 'recovery_expression', 'correlation_mode',
 			'correlation_tag', 'manual_close'
@@ -1057,12 +1053,8 @@ abstract class CTriggerGeneral extends CApiService {
 
 		$descriptions = [];
 
-		foreach ($triggers as $key => &$trigger) {
-			if (!array_key_exists($trigger['triggerid'], $_db_triggers)) {
-				self::exception(ZBX_API_ERROR_PARAMETERS, _('No permissions to referred object or it does not exist!'));
-			}
-
-			$db_trigger = $_db_triggers[$trigger['triggerid']];
+		foreach ($triggers as &$trigger) {
+			$db_trigger = $db_triggers[$trigger['triggerid']];
 			$description = array_key_exists('description', $trigger)
 				? $trigger['description']
 				: $db_trigger['description'];
@@ -1110,8 +1102,6 @@ abstract class CTriggerGeneral extends CApiService {
 					'recovery_expression' => $trigger['recovery_expression']
 				];
 			}
-
-			$db_triggers[$key] = $db_trigger;
 		}
 		unset($trigger);
 
@@ -1119,6 +1109,303 @@ abstract class CTriggerGeneral extends CApiService {
 			$descriptions = $this->populateHostIds($descriptions);
 			$this->checkDuplicates($descriptions);
 		}
+
+		$this->checkDependencies($triggers, $db_triggers);
+		$this->checkDependenciesLinks($triggers, $db_triggers);
+	}
+
+	/**
+	 * @param array $triggers
+	 * @param array $db_triggers
+	 */
+	private function addAffectedObjects(array $triggers, array &$db_triggers): void {
+		if ($this instanceof CTrigger) {
+			self::addAffectedHosts($triggers, $db_triggers);
+		}
+
+		self::addAffectedTags($triggers, $db_triggers);
+		self::addAffectedDependencies($triggers, $db_triggers);
+	}
+
+	/**
+	 * @param array $triggers
+	 * @param array $db_triggers
+	 */
+	protected static function addAffectedHosts(array $triggers, array &$db_triggers): void {
+		$triggerids = [];
+
+		foreach ($triggers as $trigger) {
+			$db_trigger = $db_triggers[$trigger['triggerid']];
+
+			if ((array_key_exists('expression', $trigger) && $trigger['expression'] !== $db_trigger['expression'])
+					|| (array_key_exists('recovery_expression', $trigger)
+						&& $trigger['recovery_expression'] !== $db_trigger['recovery_expression'])) {
+				$triggerids[] = $trigger['triggerid'];
+				$db_triggers[$trigger['triggerid']]['hosts'] = [];
+			}
+		}
+
+		if (!$triggerids) {
+			return;
+		}
+
+		$result = DBselect(
+			'SELECT DISTINCT f.triggerid,i.hostid'.
+			' FROM functions f,items i'.
+			' WHERE f.itemid=i.itemid'.
+				' AND '.dbConditionId('f.triggerid', $triggerids)
+		);
+
+		while ($row = DBfetch($result)) {
+			$db_triggers[$row['triggerid']]['hosts'][$row['hostid']] = true;
+		}
+	}
+
+	/**
+	 * @param array $triggers
+	 * @param array $db_triggers
+	 */
+	private static function addAffectedTags(array $triggers, array &$db_triggers): void {
+		$triggerids = [];
+
+		foreach ($triggers as $trigger) {
+			if (array_key_exists('tags', $trigger)) {
+				$triggerids[] = $trigger['triggerid'];
+				$db_triggers[$trigger['triggerid']]['tags'] = [];
+			}
+		}
+
+		if (!$triggerids) {
+			return;
+		}
+
+		$options = [
+			'output' => ['triggertagid', 'triggerid', 'tag', 'value'],
+			'filter' => ['triggerid' => $triggerids]
+		];
+		$db_tags = DBselect(DB::makeSql('trigger_tag', $options));
+
+		while ($db_tag = DBfetch($db_tags)) {
+			$db_triggers[$db_tag['triggerid']]['tags'][$db_tag['triggertagid']] =
+				array_diff_key($db_tag, array_flip(['triggerid']));
+		}
+	}
+
+	/**
+	 * @param array $triggers
+	 * @param array $db_triggers
+	 */
+	protected static function addAffectedDependencies(array $triggers, array &$db_triggers): void {
+		$triggerids = [];
+
+		foreach ($triggers as $trigger) {
+			$db_trigger = $db_triggers[$trigger['triggerid']];
+
+			if (array_key_exists('dependencies', $trigger) || array_key_exists('hosts', $db_trigger)) {
+				$triggerids[] = $trigger['triggerid'];
+				$db_triggers[$trigger['triggerid']]['dependencies'] = [];
+			}
+		}
+
+		if (!$triggerids) {
+			return;
+		}
+
+		$options = [
+			'output' => ['triggerdepid', 'triggerid_down', 'triggerid_up'],
+			'filter' => ['triggerid_down' => $triggerids]
+		];
+		$db_deps = DBselect(DB::makeSql('trigger_depends', $options));
+
+		while ($db_dep = DBfetch($db_deps)) {
+			$db_triggers[$db_dep['triggerid_down']]['dependencies'][$db_dep['triggerdepid']] = [
+				'triggerdepid' => $db_dep['triggerdepid'],
+				'triggerid' => $db_dep['triggerid_up']
+			];
+		}
+	}
+
+	/**
+	 * Check trigger dependencies of the given triggers.
+	 *
+	 * @param array      $triggers
+	 * @param array|null $db_triggers
+	 *
+	 * @throws APIException
+	 */
+	private function checkDependencies(array $triggers, array $db_triggers = null): void {
+		$edit_triggerids_up = [];
+
+		foreach ($triggers as $trigger) {
+			if (!array_key_exists('dependencies', $trigger)) {
+				continue;
+			}
+
+			$triggerids_up = array_column($trigger['dependencies'], 'triggerid');
+
+			if ($db_triggers === null) {
+				$edit_triggerids_up += array_flip($triggerids_up);
+			}
+			else {
+				$db_triggerids_up = array_column($db_triggers[$trigger['triggerid']]['dependencies'], 'triggerid');
+
+				$ins_triggerids_up = array_flip(array_diff($triggerids_up, $db_triggerids_up));
+				$del_triggerids_up = array_flip(array_diff($db_triggerids_up, $triggerids_up));
+
+				$edit_triggerids_up += $ins_triggerids_up + $del_triggerids_up;
+			}
+		}
+
+		if (!$edit_triggerids_up) {
+			return;
+		}
+
+		$count = API::Trigger()->get([
+			'countOutput' => true,
+			'triggerids' => array_keys($edit_triggerids_up)
+		]);
+
+		if ($this instanceof CTriggerPrototype) {
+			$trigger_prototypes_up = API::TriggerPrototype()->get([
+				'output' => [],
+				'triggerids' => array_keys($edit_triggerids_up),
+				'preservekeys' => true
+			]);
+
+			$count += count($trigger_prototypes_up);
+		}
+
+		if ($count != count($edit_triggerids_up)) {
+			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
+		}
+
+		if ($this instanceof CTriggerPrototype) {
+			$ins_dependencies = [];
+			$triggerids = [];
+
+			foreach ($triggers as $trigger) {
+				if (!array_key_exists('dependencies', $triggers)) {
+					continue;
+				}
+
+				$db_triggers_up = ($db_triggers !== null)
+					? array_column($db_triggers[$trigger['triggerid']]['dependencies'], null, 'triggerid')
+					: [];
+
+				foreach ($trigger['dependencies'] as $trigger_up) {
+					if (!array_key_exists($trigger_up['triggerid'], $db_triggers_up)
+							&& array_key_exists($trigger_up['triggerid'], $trigger_prototypes_up)) {
+						$ins_dependencies[$trigger_up['triggerid']][$trigger['triggerid']] = true;
+						$triggerids[$trigger['triggerid']] = true;
+					}
+				}
+			}
+
+			if (!$ins_dependencies) {
+				return;
+			}
+
+			$result = DBselect(
+				'SELECT DISTINCT f.triggerid,id.parent_itemid'.
+				' FROM functions f,item_discovery id'.
+				' WHERE f.itemid=id.itemid'.
+					' AND '.dbConditionId('f.triggerid', array_keys($ins_dependencies + $triggerids))
+			);
+
+			$lld_rules = [];
+
+			while ($row = DBfetch($result)) {
+				$lld_rules[$row['triggerid']] = $row['parent_itemid'];
+			}
+
+			foreach ($ins_dependencies as $triggerid_up => $triggerids) {
+				foreach ($triggerids as $triggerid) {
+					if (bccomp($lld_rules[$triggerid_up], $lld_rules[$triggerid]) != 0) {
+						self::exception(ZBX_API_ERROR_PARAMETERS,
+							_('Trigger prototype "%1$s" cannot depend on the trigger prototype "%2$s", because dependencies on trigger prototypes from another LLD rule are not allowed.')
+						);
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Check linkage of dependencies.
+	 *
+	 * @param array      $triggers
+	 * @param array|null $db_triggers
+	 */
+	protected function checkDependenciesLinks(array $triggers, array $db_triggers = null): void {
+		$ins_dependencies = [];
+		$del_dependencies = [];
+
+		foreach ($triggers as $trigger) {
+			if (!array_key_exists('dependencies', $trigger)) {
+				continue;
+			}
+
+			$db_triggers_up = ($db_triggers !== null)
+				? array_column($db_triggers[$trigger['triggerid']]['dependencies'], null, 'triggerid')
+				: [];
+
+			foreach ($trigger['dependencies'] as $trigger_up) {
+				if (array_key_exists($trigger_up['triggerid'], $db_triggers_up)) {
+					unset($db_triggers_up[$trigger_up['triggerid']]);
+				}
+				else {
+					$ins_dependencies[$trigger_up['triggerid']][$trigger['triggerid']] = true;
+				}
+			}
+
+			foreach ($db_triggers_up as $db_trigger_up) {
+				$del_dependencies[$db_trigger_up['triggerid']][$trigger['triggerid']] = true;
+			}
+		}
+
+		if ($ins_dependencies) {
+			if ($this instanceof CTriggerPrototype) {
+				$options = [
+					'output' => ['triggerid', 'flags'],
+					'triggerids' => array_keys($ins_dependencies)
+				];
+				$result = DBselect(DB::makeSql('triggers', $options));
+
+				$ins_dependencies_prototypes = [];
+
+				while ($row = DBfetch($result)) {
+					if ($row['flags'] == ZBX_FLAG_DISCOVERY_PROTOTYPE) {
+
+						/*
+						 * Trigger cannot depend on trigger prototypes, so it's enough to check circular dependencies
+						 * only among the trigger prototypes.
+						 */
+						$ins_dependencies_prototypes[$row['triggerid']] = $ins_dependencies[$row['triggerid']];
+
+						/*
+						 * Since the trigger prototypes can depend only on trigger prototypes from the same LLD rule,
+						 * for such dependencies it is not necessary to check the dependencies of host and template
+						 * triggers. Only dependencies on triggers are required to be checked.
+						 */
+						unset($ins_dependencies[$row['triggerid']]);
+					}
+				}
+			}
+
+			if ($db_triggers !== null) {
+				if ($this instanceof CTriggerPrototype && $ins_dependencies_prototypes) {
+					self::checkCircularDependencies($ins_dependencies_prototypes, $del_dependencies);
+				}
+				else {
+					self::checkCircularDependencies($ins_dependencies, $del_dependencies);
+				}
+			}
+
+			$trigger_hosts = self::getTriggerHosts($ins_dependencies);
+
+			self::checkDependenciesOfHostTriggers($ins_dependencies, $trigger_hosts);
+			self::checkDependenciesOfTemplateTriggers($ins_dependencies, $trigger_hosts);
+		}
 	}
 
 	/**
@@ -1248,7 +1535,7 @@ abstract class CTriggerGeneral extends CApiService {
 		$this->implode_expressions($triggers, $db_triggers, $triggers_functions, $inherited);
 
 		foreach ($triggers as $tnum => $trigger) {
-			$db_trigger = $db_triggers[$tnum];
+			$db_trigger = $db_triggers[$trigger['triggerid']];
 			$upd_trigger = ['values' => [], 'where' => ['triggerid' => $trigger['triggerid']]];
 
 			if (array_key_exists($tnum, $triggers_functions)) {
@@ -1361,7 +1648,7 @@ abstract class CTriggerGeneral extends CApiService {
 
 		if (!$inherited) {
 			$resource = ($this instanceof CTrigger) ? CAudit::RESOURCE_TRIGGER : CAudit::RESOURCE_TRIGGER_PROTOTYPE;
-			$this->addAuditBulk(CAudit::ACTION_UPDATE, $resource, $save_triggers, zbx_toHash($db_triggers, 'triggerid'));
+			$this->addAuditBulk(CAudit::ACTION_UPDATE, $resource, $save_triggers, $db_triggers);
 		}
 	}
 
@@ -1379,9 +1666,9 @@ abstract class CTriggerGeneral extends CApiService {
 	 * @param int        $triggers[<tnum>]['recovery_mode']          [IN]
 	 * @param string     $triggers[<tnum>]['recovery_expression']    [IN/OUT]
 	 * @param array|null $db_triggers                                [IN]
-	 * @param string     $db_triggers[<tnum>]['triggerid']           [IN]
-	 * @param string     $db_triggers[<tnum>]['expression']          [IN]
-	 * @param string     $db_triggers[<tnum>]['recovery_expression'] [IN]
+	 * @param string     $db_triggers[<triggerid>]['triggerid']           [IN]
+	 * @param string     $db_triggers[<triggerid>]['expression']          [IN]
+	 * @param string     $db_triggers[<triggerid>]['recovery_expression'] [IN]
 	 * @param array      $triggers_functions                         [OUT] array of the new functions which must be
 	 *                                                                     inserted into DB
 	 * @param string     $triggers_functions[<tnum>][]['functionid'] [OUT]
@@ -1438,10 +1725,10 @@ abstract class CTriggerGeneral extends CApiService {
 		$hosts_keys = [];
 		$functions_num = 0;
 
-		foreach ($triggers as $tnum => $trigger) {
+		foreach ($triggers as $trigger) {
 			$expressions_changed = ($db_triggers === null
-				|| ($trigger['expression'] !== $db_triggers[$tnum]['expression']
-				|| $trigger['recovery_expression'] !== $db_triggers[$tnum]['recovery_expression']));
+				|| ($trigger['expression'] !== $db_triggers[$trigger['triggerid']]['expression']
+				|| $trigger['recovery_expression'] !== $db_triggers[$trigger['triggerid']]['recovery_expression']));
 
 			if (!$expressions_changed) {
 				continue;
@@ -1577,8 +1864,8 @@ abstract class CTriggerGeneral extends CApiService {
 
 		foreach ($triggers as $tnum => &$trigger) {
 			$expressions_changed = ($db_triggers === null
-				|| ($trigger['expression'] !== $db_triggers[$tnum]['expression']
-				|| $trigger['recovery_expression'] !== $db_triggers[$tnum]['recovery_expression']));
+				|| ($trigger['expression'] !== $db_triggers[$trigger['triggerid']]['expression']
+				|| $trigger['recovery_expression'] !== $db_triggers[$trigger['triggerid']]['recovery_expression']));
 
 			if (!$expressions_changed) {
 				continue;
@@ -1672,12 +1959,12 @@ abstract class CTriggerGeneral extends CApiService {
 
 			// Triggers with children cannot be moved from one template to another host or template.
 			if ($class === 'CTrigger' && $db_triggers !== null && $expressions_changed) {
-				$expression_parser->parse($db_triggers[$tnum]['expression']);
+				$expression_parser->parse($db_triggers[$trigger['triggerid']]['expression']);
 				$old_hosts1 = $expression_parser->getResult()->getHosts();
 				$old_hosts2 = [];
 
 				if ($trigger['recovery_mode'] == ZBX_RECOVERY_MODE_RECOVERY_EXPRESSION) {
-					$expression_parser->parse($db_triggers[$tnum]['recovery_expression']);
+					$expression_parser->parse($db_triggers[$trigger['triggerid']]['recovery_expression']);
 					$old_hosts2 = $expression_parser->getResult()->getHosts();
 				}
 
@@ -1690,7 +1977,7 @@ abstract class CTriggerGeneral extends CApiService {
 				}
 
 				if ($is_moved) {
-					$moved_triggers[$db_triggers[$tnum]['triggerid']] = ['description' => $trigger['description']];
+					$moved_triggers[$trigger['triggerid']] = ['description' => $trigger['description']];
 				}
 			}
 
@@ -1717,7 +2004,7 @@ abstract class CTriggerGeneral extends CApiService {
 					));
 				}
 				elseif ($db_triggers !== null
-						&& !idcmp($lld_ruleids[0], $db_triggers[$tnum]['discoveryRule']['itemid'])) {
+						&& !idcmp($lld_ruleids[0], $db_triggers[$trigger['triggerid']]['discoveryRule']['itemid'])) {
 					self::exception(ZBX_API_ERROR_PARAMETERS, _s('Cannot update trigger prototype "%1$s": %2$s.',
 						$trigger['description'], _('trigger prototype cannot be moved to another template or host')
 					));
@@ -1742,8 +2029,8 @@ abstract class CTriggerGeneral extends CApiService {
 		// Replace func(/host/item) macros with {<functionid>}.
 		foreach ($triggers as $tnum => &$trigger) {
 			$expressions_changed = ($db_triggers === null
-				|| ($trigger['expression'] !== $db_triggers[$tnum]['expression']
-				|| $trigger['recovery_expression'] !== $db_triggers[$tnum]['recovery_expression']));
+				|| ($trigger['expression'] !== $db_triggers[$trigger['triggerid']]['expression']
+				|| $trigger['recovery_expression'] !== $db_triggers[$trigger['triggerid']]['recovery_expression']));
 
 			if (!$expressions_changed) {
 				continue;
@@ -1921,4 +2208,1039 @@ abstract class CTriggerGeneral extends CApiService {
 
 		$this->inherit($triggers, $data['hostids']);
 	}
+
+	/**
+	 * Checks if the given dependencies already exist.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 *
+	 * @throws APIException
+	 */
+	protected static function checkDependencyDuplicates(array $trigger_dependencies) {
+		$all_triggerids = [];
+
+		foreach ($trigger_dependencies as $triggerids) {
+			$all_triggerids += $triggerids;
+		}
+
+		$options = [
+			'output' => ['triggerid_down', 'triggerid_up'],
+			'filter' => [
+				'triggerid_down' => array_keys($all_triggerids),
+				'triggerid_up' => array_keys($trigger_dependencies)
+			]
+		];
+		$result = DBselect(DB::makeSql('trigger_depends', $options));
+
+		while ($row = DBfetch($result)) {
+			if (array_key_exists($row['triggerid_up'], $trigger_dependencies)
+					&& in_array($row['triggerid_down'], $trigger_dependencies[$row['triggerid_up']])) {
+				$duplicates = DB::select('triggers', [
+					'output' => ['description', 'flags'],
+					'triggerids' => [$row['triggerid_down'], $row['triggerid_up']],
+					'preservekeys' => true
+				]);
+
+				if ($duplicates[$row['triggerid_down']]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL) {
+					$error = _('The dependency of trigger "%1$s" on trigger "%2$s" already exists.');
+				}
+				else {
+					$error = ($duplicates[$row['triggerid_up']]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+						? _('The dependency of trigger prototype "%1$s" on trigger "%2$s" already exists.')
+						: _('The dependency of trigger prototype "%1$s" on trigger prototype "%2$s" already exists.');
+				}
+
+				self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error,
+					$duplicates[$row['triggerid_down']]['description'],
+					$duplicates[$row['triggerid_up']]['description']
+				));
+			}
+		}
+	}
+
+	/**
+	 * Check whether circular linkage occurs as a result of the given changes in trigger dependencies.
+	 *
+	 * @param array $ins_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $del_dependencies[<triggerid_up>][<triggerid>]
+	 * @param bool  $inherited  Whether the check gets performed during inherit.
+	 *
+	 * @throws APIException
+	 */
+	protected static function checkCircularDependencies(array $ins_dependencies, array $del_dependencies = [],
+			bool $inherited = false): void {
+		$links = [];
+		$_triggerids_down = $ins_dependencies;
+
+		do {
+			$options = [
+				'output' => ['triggerid_up', 'triggerid_down'],
+				'filter' => [
+					'triggerid_down' => array_keys($_triggerids_down)
+				]
+			];
+			$result = DBselect(DB::makeSql('trigger_depends', $options));
+
+			$_triggerids_down = [];
+
+			while ($row = DBfetch($result)) {
+				if (array_key_exists($row['triggerid_up'], $del_dependencies)
+						&& array_key_exists($row['triggerid_down'], $del_dependencies[$row['triggerid_up']])) {
+					continue;
+				}
+
+				if (!array_key_exists($row['triggerid_up'], $links)) {
+					$_triggerids_down[$row['triggerid_up']] = true;
+				}
+
+				$links[$row['triggerid_up']][$row['triggerid_down']] = true;
+			}
+		} while ($_triggerids_down);
+
+		foreach ($ins_dependencies as $triggerid_up => $triggerids) {
+			if (array_key_exists($triggerid_up, $links)) {
+				$links[$triggerid_up] += $triggerids;
+			}
+			else {
+				$links[$triggerid_up] = $triggerids;
+			}
+		}
+
+		foreach ($ins_dependencies as $triggerid_up => $triggerids) {
+			foreach ($triggerids as $triggerid => $foo) {
+				if (array_key_exists($triggerid, $links)) {
+					$links_path = [$triggerid => true];
+
+					if (self::circularLinkageExists($links, $triggerid_up, $links[$triggerid], $links_path)) {
+						$trigger_up_name = '';
+
+						$triggers = DB::select('triggers', [
+							'output' => ['description', 'flags'],
+							'triggerids' => array_keys($links_path + [$triggerid_up => true]),
+							'preservekeys' => true
+						]);
+
+						foreach ($triggers as $_triggerid => $trigger) {
+							$description = '"'.$trigger['description'].'"';
+
+							if (bccomp($_triggerid, $triggerid_up) == 0) {
+								$trigger_up_name = $description;
+							}
+							else {
+								$links_path[$_triggerid] = $description;
+							}
+						}
+
+						$circular_linkage = (bccomp($triggerid_up, $triggerid) == 0)
+							? $trigger_up_name.' -> '.$trigger_up_name
+							: $trigger_up_name.' -> '.implode(' -> ', $links_path).' -> '.$trigger_up_name;
+
+						if ($inherited) {
+							$host = DBfetch(DBselect(
+								'SELECT DISTINCT h.host,h.status'.
+								' FROM functions f,items i,hosts h'.
+								' WHERE f.itemid=i.itemid'.
+									' AND i.hostid=h.hostid'.
+									' AND '.dbConditionId('f.triggerid', [$triggerid_up])
+							));
+
+							if ($host['status'] == HOST_STATUS_TEMPLATE) {
+								$error = ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+									? _('Trigger "%1$s" cannot depend on the trigger "%2$s", because a circular linkage (%3$s) would occur for template "%4$s".')
+									: _('Trigger prototype "%1$s" cannot depend on the trigger prototype "%2$s", because a circular linkage (%3$s) would occur for template "%4$s".');
+							}
+							else {
+								$error = ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+									? _('Trigger "%1$s" cannot depend on the trigger "%2$s", because a circular linkage (%3$s) would occur for host "%4$s".')
+									: _('Trigger prototype "%1$s" cannot depend on the trigger prototype "%2$s", because a circular linkage (%3$s) would occur for host "%4$s".');
+							}
+
+							self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error,
+								$triggers[$triggerid]['description'], $triggers[$triggerid_up]['description'],
+								$circular_linkage, $host['host']
+							));
+						}
+						else {
+							$error = ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+								? _('Trigger "%1$s" cannot depend on the trigger "%2$s", because a circular linkage (%3$s) would occur.')
+								: _('Trigger prototype "%1$s" cannot depend on the trigger prototype "%2$s", because a circular linkage (%3$s) would occur.');
+
+							self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error,
+								$triggers[$triggerid]['description'], $triggers[$triggerid_up]['description'],
+								$circular_linkage
+							));
+						}
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Recursively check whether the trigger, which a dependency is being set on, produces a circular linkage.
+	 *
+	 * @param array  $links[<triggerid_up>][<triggerid>]
+	 * @param string $triggerid_up
+	 * @param array  $triggerids[<triggerid>]
+	 * @param array  $links_path                          Circular linkage path, collected performing the check.
+	 *
+	 * @return bool
+	 */
+	private static function circularLinkageExists(array $links, string $triggerid_up, array $triggerids,
+			array &$links_path): bool {
+		if (array_key_exists($triggerid_up, $triggerids)) {
+			return true;
+		}
+
+		$_links_path = $links_path;
+
+		foreach ($triggerids as $triggerid => $foo) {
+			if (array_key_exists($triggerid, $links)) {
+				$links_path = $_links_path;
+				$triggerid_links = array_diff_key($links[$triggerid], $links_path);
+
+				if ($triggerid_links) {
+					$links_path[$triggerid] = true;
+
+					if (self::circularLinkageExists($links, $triggerid_up, $triggerid_links, $links_path)) {
+						return true;
+					}
+				}
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Get hosts data of all triggers given in trigger dependencies array.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 *
+	 * @return array
+	 */
+	public static function getTriggerHosts(array $trigger_dependencies): array {
+		$all_triggerids = $trigger_dependencies;
+
+		foreach ($trigger_dependencies as $triggerids) {
+			$all_triggerids += $triggerids;
+		}
+
+		$result = DBselect(
+			'SELECT DISTINCT f.triggerid,h.hostid,h.status'.
+			' FROM functions f,items i,hosts h'.
+			' WHERE f.itemid=i.itemid'.
+				' AND i.hostid=h.hostid'.
+				' AND '.dbConditionId('f.triggerid', array_keys($all_triggerids))
+		);
+
+		$trigger_hosts = [];
+
+		while ($row = DBfetch($result)) {
+			// Each trigger can have either only templateids or only hostids.
+			if ($row['status'] == HOST_STATUS_TEMPLATE) {
+				$trigger_hosts[$row['triggerid']]['templateids'][$row['hostid']] = true;
+			}
+			else {
+				$trigger_hosts[$row['triggerid']]['hostids'][$row['hostid']] = true;
+			}
+		}
+
+		return $trigger_hosts;
+	}
+
+	/**
+	 * Check whether the trigger dependencies are correctly set for host triggers.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $trigger_hosts
+	 *
+	 * @throws APIException
+	 */
+	public static function checkDependenciesOfHostTriggers(array $trigger_dependencies, array $trigger_hosts): void {
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			if (array_key_exists('templateids', $trigger_hosts[$triggerid_up])) {
+				foreach ($triggerids as $triggerid => $foo) {
+					if (array_key_exists('hostids', $trigger_hosts[$triggerid])) {
+						$triggers = DB::select('triggers', [
+							'output' => ['description', 'flags'],
+							'triggerids' => [$triggerid, $triggerid_up],
+							'preservekeys' => true
+						]);
+
+						$error = ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+							? _('Trigger "%1$s" cannot depend on the trigger "%2$s", because dependencies of host triggers on template triggers are not allowed.')
+							: _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s", because dependencies of host triggers on template triggers are not allowed.');
+
+						self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $triggers[$triggerid]['description'],
+							$triggers[$triggerid_up]['description']
+						));
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Check whether the trigger dependencies are correctly set for template triggers.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $trigger_hosts
+	 *
+	 * @throws APIException
+	 */
+	public static function checkDependenciesOfTemplateTriggers(array $trigger_dependencies,
+			array $trigger_hosts): void {
+		/*
+		 * From the given trigger dependencies we should keep only the dependencies of the template triggers. There is
+		 * also no need to check the dependencies on triggers from the same template, because that is considered a
+		 * valid case. Thus, among the triggers that the template triggers depends on, we should only keep triggers from
+		 * other templates and hosts.
+		 */
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			$templateids_up = array_key_exists('templateids', $trigger_hosts[$triggerid_up])
+				? $trigger_hosts[$triggerid_up]['templateids']
+				: [];
+
+			foreach ($triggerids as $triggerid => $foo) {
+				/*
+				 * If trigger-up and dependent trigger have at least one common template, even if they also have
+				 * other templates, it is important to understand that at the moment of the trigger dependency
+				 * validation all of those different templates are already linked to all child templates,
+				 * so there is no need to check them again.
+				 */
+				if (!array_key_exists('templateids', $trigger_hosts[$triggerid])
+						|| array_intersect_key($templateids_up, $trigger_hosts[$triggerid]['templateids'])) {
+					unset($trigger_dependencies[$triggerid_up][$triggerid]);
+				}
+			}
+
+			if (!$trigger_dependencies[$triggerid_up]) {
+				unset($trigger_dependencies[$triggerid_up]);
+			}
+		}
+
+		if (!$trigger_dependencies) {
+			return;
+		}
+
+		self::checkTriggersUpNotFromParentTemplates($trigger_dependencies, $trigger_hosts);
+		self::checkTriggersUpNotFromChildTemplatesOrHosts($trigger_dependencies, $trigger_hosts);
+		self::checkTriggersUpTemplatesAreLinkedToChildTemplates($trigger_dependencies, $trigger_hosts);
+	}
+
+	/**
+	 * Check that the triggers-up of the given trigger dependencies do not come from parent templates of dependent
+	 * triggers.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $trigger_hosts
+	 *
+	 * @throws APIException
+	 */
+	private static function checkTriggersUpNotFromParentTemplates(array $trigger_dependencies, array $trigger_hosts): void {
+		$templateids = [];
+		$template_triggers_up = [];
+		$dependency_templates = [];
+
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			if (!array_key_exists('templateids', $trigger_hosts[$triggerid_up])) {
+				continue;
+			}
+
+			$templateids_up = [];
+
+			foreach ($trigger_hosts[$triggerid_up]['templateids'] as $templateid => $foo) {
+				$template_triggers_up[$templateid][] = $triggerid_up;
+				$templateids_up[$templateid] = true;
+			}
+
+			foreach ($triggerids as $triggerid => $foo) {
+				foreach ($trigger_hosts[$triggerid]['templateids'] as $templateid => $foo) {
+					if (!array_key_exists($templateid, $dependency_templates)) {
+						$dependency_templates[$templateid] = [];
+					}
+
+					$dependency_templates[$templateid] += $templateids_up;
+				}
+
+				$templateids += $trigger_hosts[$triggerid]['templateids'];
+			}
+		}
+
+		$_templateids = $templateids;
+		$template_links = [];
+
+		do {
+			$options = [
+				'output' => ['hostid', 'templateid'],
+				'filter' => ['hostid' => array_keys($_templateids)]
+			];
+			$result = DBselect(DB::makeSql('hosts_templates', $options));
+
+			$_templateids = [];
+
+			while ($row = DBfetch($result)) {
+				$template_links[$row['hostid']][$row['templateid']] = true;
+
+				if (!array_key_exists($row['templateid'], $template_links)) {
+					$_templateids[$row['templateid']] = true;
+				}
+			}
+		} while ($_templateids);
+
+		if (!$template_links) {
+			return;
+		}
+
+		// Check if the trigger-up is a trigger from the parent template of the dependent trigger.
+		foreach ($dependency_templates as $templateid => $templateids_up) {
+			if (array_key_exists($templateid, $template_links)) {
+				foreach ($templateids_up as $templateid_up => $foo) {
+					if (self::checkTemplateUpExistsInTemplateLinks($template_links, $templateid, $templateid_up)) {
+						foreach ($template_triggers_up[$templateid_up] as $triggerid_up) {
+							foreach ($trigger_dependencies[$triggerid_up] as $triggerid => $foo) {
+								if (array_key_exists($templateid, $trigger_hosts[$triggerid]['templateids'])) {
+									break 2;
+								}
+							}
+						}
+
+						$triggers = DB::select('triggers', [
+							'output' => ['description', 'flags'],
+							'triggerids' => [$triggerid, $triggerid_up],
+							'preservekeys' => true
+						]);
+
+						$templates = DB::select('hosts', [
+							'output' => ['host'],
+							'hostids' => $templateid_up
+						]);
+
+						$error = ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL)
+							? _('Trigger "%1$s" cannot depend on the trigger "%2$s" from the template "%3$s", because dependencies on triggers from the parent template are not allowed.')
+							: _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s" from the template "%3$s", because dependencies on triggers from the parent template are not allowed.');
+
+						self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $triggers[$triggerid]['description'],
+							$triggers[$triggerid_up]['description'], $templates[0]['host']
+						));
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Check that the triggers-up of the given trigger dependencies are not from the child templates or hosts of the
+	 * dependent triggers.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $trigger_hosts
+	 *
+	 * @throws APIException
+	 */
+	private static function checkTriggersUpNotFromChildTemplatesOrHosts(array $trigger_dependencies,
+			array $trigger_hosts): void {
+		$templateids = [];
+		$template_triggers_up = [];
+		$dependency_templates = [];
+
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			$templateids_up = [];
+
+			if (array_key_exists('templateids', $trigger_hosts[$triggerid_up])) {
+				foreach ($trigger_hosts[$triggerid_up]['templateids'] as $templateid => $foo) {
+					$template_triggers_up[$templateid][] = $triggerid_up;
+					$templateids_up[$templateid] = true;
+				}
+			}
+			else {
+				foreach ($trigger_hosts[$triggerid_up]['hostids'] as $hostid => $foo) {
+					$template_triggers_up[$hostid][] = $triggerid_up;
+					$templateids_up[$hostid] = true;
+				}
+			}
+
+			foreach ($triggerids as $triggerid => $foo) {
+				foreach ($trigger_hosts[$triggerid]['templateids'] as $templateid => $foo) {
+					if (!array_key_exists($templateid, $dependency_templates)) {
+						$dependency_templates[$templateid] = [];
+					}
+
+					$dependency_templates[$templateid] += $templateids_up;
+				}
+
+				$templateids += $trigger_hosts[$triggerid]['templateids'];
+			}
+		}
+
+		$template_links = [];
+
+		do {
+			$options = [
+				'output' => ['hostid', 'templateid'],
+				'filter' => ['templateid' => array_keys($templateids)]
+			];
+			$result = DBselect(DB::makeSql('hosts_templates', $options));
+
+			$templateids = [];
+
+			while ($row = DBfetch($result)) {
+				$template_links[$row['templateid']][$row['hostid']] = true;
+
+				if (!array_key_exists($row['hostid'], $template_links)) {
+					$templateids[$row['hostid']] = true;
+				}
+			}
+		} while ($templateids);
+
+		if (!$template_links) {
+			return;
+		}
+
+		// Check if each trigger-up is a trigger from the child template or host of the dependent trigger.
+		foreach ($dependency_templates as $templateid => $templateids_up) {
+			if (array_key_exists($templateid, $template_links)) {
+				foreach ($templateids_up as $templateid_up => $foo) {
+					if (self::checkTemplateUpExistsInTemplateLinks($template_links, $templateid, $templateid_up)) {
+						foreach ($template_triggers_up[$templateid_up] as $triggerid_up) {
+							foreach ($trigger_dependencies[$triggerid_up] as $triggerid => $foo) {
+								if (array_key_exists($templateid, $trigger_hosts[$triggerid]['templateids'])) {
+									break 2;
+								}
+							}
+						}
+
+						$triggers = DB::select('triggers', [
+							'output' => ['description', 'flags'],
+							'triggerids' => [$triggerid, $triggerid_up],
+							'preservekeys' => true
+						]);
+
+						$templates = DB::select('hosts', [
+							'output' => ['host', 'status'],
+							'hostids' => $templateid_up
+						]);
+
+						if ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL) {
+							$error = ($templates[0]['status'] == HOST_STATUS_TEMPLATE)
+								? _('Trigger "%1$s" cannot depend on the trigger "%2$s" from the template "%3$s", because dependencies on triggers from a child template or host are not allowed.')
+								: _('Trigger "%1$s" cannot depend on the trigger "%2$s" from the host "%3$s", because dependencies on triggers from a child template or host are not allowed.');
+						}
+						else {
+							$error = ($templates[0]['status'] == HOST_STATUS_TEMPLATE)
+								? _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s" from the template "%3$s", because dependencies on triggers from a child template or host are not allowed.')
+								: _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s" from the host "%3$s", because dependencies on triggers from a child template or host are not allowed.');
+						}
+
+						self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $triggers[$triggerid]['description'],
+							$triggers[$triggerid_up]['description'], $templates[0]['host']
+						));
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Recursively check if the given template-up exists in the chain of the given template links.
+	 *
+	 * @param array  $template_links[<templateid>][<templateid_up>]
+	 * @param string $templateid
+	 * @param string $templateid_up
+	 *
+	 * @return bool
+	 */
+	private static function checkTemplateUpExistsInTemplateLinks(array $template_links, string $templateid,
+			string $templateid_up): bool {
+		if (array_key_exists($templateid_up, $template_links[$templateid])) {
+			return true;
+		}
+
+		foreach ($template_links[$templateid] as $_templateid => $foo) {
+			if (array_key_exists($_templateid, $template_links)
+					&& self::checkTemplateUpExistsInTemplateLinks($template_links, $_templateid, $templateid_up)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check if the triggers-up templates of the given trigger dependencies are linked to child templates of the
+	 * dependent triggers.
+	 *
+	 * @param array $trigger_dependencies[<triggerid_up>][<triggerid>]
+	 * @param array $trigger_hosts
+	 *
+	 * @throws APIException
+	 */
+	private static function checkTriggersUpTemplatesAreLinkedToChildTemplates(array $trigger_dependencies,
+			array $trigger_hosts): void {
+		$templateids_up = [];
+		$templateids = [];
+
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			if (!array_key_exists('templateids', $trigger_hosts[$triggerid_up])) {
+				unset($trigger_dependencies[$triggerid_up]);
+				continue;
+			}
+
+			$templateids_up += $trigger_hosts[$triggerid_up]['templateids'];
+
+			foreach ($triggerids as $triggerid => $foo) {
+				$templateids += $trigger_hosts[$triggerid]['templateids'];
+			}
+		}
+
+		$options = [
+			'output' => ['templateid', 'hostid'],
+			'filter' => [
+				'templateid' => array_keys($templateids)
+			]
+		];
+		$result = DBselect(DB::makeSql('hosts_templates', $options));
+
+		$template_links = [];
+
+		while ($row = DBfetch($result)) {
+			$template_links[$row['templateid']][$row['hostid']] = [];
+		}
+
+		$result = DBselect(
+			'SELECT ht.templateid,ht.hostid,htt.templateid AS host_templateid'.
+			' FROM hosts_templates ht,hosts_templates htt'.
+			' WHERE ht.hostid=htt.hostid'.
+				' AND ht.templateid!=htt.templateid'.
+				' AND '.dbConditionId('ht.templateid', array_keys($templateids)).
+				' AND '.dbConditionId('htt.templateid', array_keys($templateids_up))
+		);
+
+		while ($row = DBfetch($result)) {
+			$template_links[$row['templateid']][$row['hostid']][$row['host_templateid']] = true;
+		}
+
+		foreach ($trigger_dependencies as $triggerid_up => $triggerids) {
+			/*
+			 * If trigger belongs to more than one template, then it is not possible to link only part of them to
+			 * another host or template. That means each template ID of that trigger would have the same hosts
+			 * in template links. And vice versa, if at least one of the trigger templates was not found in template
+			 * links, then the trigger is not inherited further.
+			 */
+			$templateid_up = key($trigger_hosts[$triggerid_up]['templateids']);
+
+			foreach ($triggerids as $triggerid => $foo) {
+				$templateid = key($trigger_hosts[$triggerid]['templateids']);
+
+				if (!array_key_exists($templateid, $template_links)) {
+					continue;
+				}
+
+				foreach ($template_links[$templateid] as $hostid => $host_templateids) {
+					if (!array_key_exists($templateid_up, $host_templateids)) {
+						$triggers = DB::select('triggers', [
+							'output' => ['description', 'flags'],
+							'triggerids' => [$triggerid, $triggerid_up],
+							'preservekeys' => true
+						]);
+
+						$hosts = DB::select('hosts', [
+							'output' => ['host', 'status'],
+							'hostids' => [$templateid_up, $hostid],
+							'preservekeys' => true
+						]);
+
+						if ($triggers[$triggerid]['flags'] == ZBX_FLAG_DISCOVERY_NORMAL) {
+							$error = ($hosts[$hostid]['status'] == HOST_STATUS_TEMPLATE)
+								? _('Trigger "%1$s" cannot depend on the trigger "%2$s", because the template "%3$s" is not linked to the template "%4$s".')
+								: _('Trigger "%1$s" cannot depend on the trigger "%2$s", because the template "%3$s" is not linked to the host "%4$s".');
+						}
+						else {
+							$error = ($hosts[$hostid]['status'] == HOST_STATUS_TEMPLATE)
+								? _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s", because the template "%3$s" is not linked to the template "%4$s".')
+								: _('Trigger prototype "%1$s" cannot depend on the trigger "%2$s", because the template "%3$s" is not linked to the host "%4$s".');
+						}
+
+						self::exception(ZBX_API_ERROR_PARAMETERS, sprintf($error, $triggers[$triggerid]['description'],
+							$triggers[$triggerid_up]['description'], $hosts[$templateid_up]['host'],
+							$hosts[$hostid]['host']
+						));
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Update the trigger dependencies.
+	 *
+	 * @param array      $triggers
+	 * @param array|null $db_triggers
+	 */
+	public static function updateDependencies(array &$triggers, array $db_triggers = null): void {
+		$ins_trigger_deps = [];
+		$del_triggerdepids = [];
+		$edit_dependencies = [];
+
+		foreach ($triggers as &$trigger) {
+			if (!array_key_exists('dependencies', $trigger)) {
+				continue;
+			}
+
+			$db_triggers_up = ($db_triggers !== null)
+				? array_column($db_triggers[$trigger['triggerid']]['dependencies'], null, 'triggerid')
+				: [];
+
+			foreach ($trigger['dependencies'] as &$trigger_up) {
+				if (array_key_exists($trigger_up['triggerid'], $db_triggers_up)) {
+					$trigger_up['triggerdepid'] = $db_triggers_up[$trigger_up['triggerid']]['triggerdepid'];
+					unset($db_triggers_up[$trigger_up['triggerid']]);
+				}
+				else {
+					$ins_trigger_deps[] = [
+						'triggerid_down' => $trigger['triggerid'],
+						'triggerid_up' => $trigger_up['triggerid']
+					];
+
+					$edit_dependencies[$trigger['triggerid']][$trigger_up['triggerid']] = true;
+				}
+			}
+			unset($trigger_up);
+
+			foreach ($db_triggers_up as $db_trigger_up) {
+				$del_triggerdepids[] = $db_trigger_up['triggerdepid'];
+
+				$edit_dependencies[$trigger['triggerid']][$db_trigger_up['triggerid']] = false;
+			}
+		}
+		unset($trigger);
+
+		if ($del_triggerdepids) {
+			DB::delete('trigger_depends', ['triggerdepid' => $del_triggerdepids]);
+		}
+
+		if ($ins_trigger_deps) {
+			$triggerdepids = DB::insertBatch('trigger_depends', $ins_trigger_deps);
+		}
+
+		foreach ($triggers as &$trigger) {
+			if (!array_key_exists('dependencies', $trigger)) {
+				continue;
+			}
+
+			foreach ($trigger['dependencies'] as &$trigger_up) {
+				if (!array_key_exists('triggerdepid', $trigger_up)) {
+					$trigger_up['triggerdepid'] = array_shift($triggerdepids);
+				}
+			}
+			unset($trigger_up);
+		}
+		unset($trigger);
+
+		if ($edit_dependencies) {
+			$edit_dependencies = self::getTemplatedDependencies($edit_dependencies);
+
+			if ($edit_dependencies) {
+				self::inheritDependencies($edit_dependencies);
+			}
+		}
+	}
+
+	/**
+	 * Filter for dependencies whose dependent triggers belong to templates that are further linked
+	 * to some templates or hosts.
+	 *
+	 * @param array $edit_dependencies[<triggerid>][<triggerid_up>]
+	 *
+	 * @return array
+	 */
+	protected static function getTemplatedDependencies(array $edit_dependencies): array {
+		$triggerids = DBfetchColumn(DBselect(
+			'SELECT DISTINCT f.triggerid'.
+			' FROM functions f,items i,hosts h'.
+			' WHERE f.itemid=i.itemid'.
+				' AND i.hostid=h.hostid'.
+				' AND '.dbConditionId('f.triggerid', array_keys($edit_dependencies)).
+				' AND '.dbConditionInt('h.status', [HOST_STATUS_TEMPLATE]).
+				' AND EXISTS('.
+					'SELECT NULL'.
+					' FROM hosts_templates ht'.
+					' WHERE ht.templateid=i.hostid'.
+				')'
+		), 'triggerid');
+
+		return array_intersect_key($edit_dependencies, array_flip($triggerids));
+	}
+
+	/**
+	 * Inherit the given trigger dependencies.
+	 *
+	 * @param array $edit_dependencies[<triggerid>][<triggerid_up>]
+	 * @param array $hostids
+	 */
+	protected static function inheritDependencies(array $edit_dependencies, array $hostids = null): void {
+		$all_triggerids = $edit_dependencies;
+		$all_triggerids_up = [];
+
+		foreach ($edit_dependencies as $triggerids_up) {
+			$all_triggerids += $triggerids_up;
+			$all_triggerids_up += $triggerids_up;
+		}
+
+		$hostids_condition = ($hostids !== null) ? ' AND '.dbConditionId('i.hostid', $hostids) : '';
+
+		$result = DBselect(
+			'SELECT DISTINCT t.templateid,t.triggerid,t.flags,i.hostid'.
+			' FROM triggers t,functions f,items i'.
+			' WHERE t.triggerid=f.triggerid'.
+				' AND f.itemid=i.itemid'.
+				' AND '.dbConditionId('t.templateid', array_keys($all_triggerids)).
+				$hostids_condition
+		);
+
+		$trigger_flags = [];
+		$trigger_links = [];
+		$tpl_triggerids_up = [];
+
+		while ($row = DBfetch($result)) {
+			$trigger_links[$row['templateid']][$row['hostid']] = $row['triggerid'];
+			$trigger_flags[$row['triggerid']] = $row['flags'];
+
+			if (array_key_exists($row['templateid'], $all_triggerids_up)) {
+				$tpl_triggerids_up[$row['templateid']] = true;
+			}
+		}
+
+		$del_triggerdepids = [];
+		$_edit_dependencies = [];
+
+		if ($tpl_triggerids_up) {
+			if ($hostids === null) {
+				$result = DBselect(
+					'SELECT DISTINCT t.triggerid,td.triggerid_up,td.triggerdepid,i.hostid'.
+					' FROM triggers t,trigger_depends td,triggers tt,functions f,items i'.
+					' WHERE t.triggerid=td.triggerid_down'.
+						' AND td.triggerid_up=tt.triggerid'.
+						' AND tt.triggerid=f.triggerid'.
+						' AND f.itemid=i.itemid'.
+						' AND '.dbConditionId('t.templateid', array_keys($edit_dependencies)).
+						' AND '.dbConditionId('tt.templateid', array_keys($tpl_triggerids_up))
+				);
+			}
+			else {
+				$result = DBselect(
+					'SELECT DISTINCT t.triggerid,td.triggerid_up,td.triggerdepid,ii.hostid'.
+					' FROM triggers t,functions f,items i,trigger_depends td,triggers tt,functions ff,items ii'.
+					' WHERE t.triggerid=f.triggerid'.
+						' AND f.itemid=i.itemid'.
+						' AND t.triggerid=td.triggerid_down'.
+						' AND td.triggerid_up=tt.triggerid'.
+						' AND tt.triggerid=ff.triggerid'.
+						' AND ff.itemid=ii.itemid'.
+						' AND '.dbConditionId('t.templateid', array_keys($edit_dependencies)).
+						' AND '.dbConditionId('i.hostid', $hostids).
+						' AND '.dbConditionId('tt.templateid', array_keys($tpl_triggerids_up))
+				);
+			}
+
+			$tpl_child_dependencies = [];
+
+			while ($row = DBfetch($result)) {
+				$tpl_child_dependencies[$row['triggerid']][$row['triggerid_up']][$row['hostid']] = $row['triggerdepid'];
+			}
+
+			foreach ($edit_dependencies as $triggerid => $triggerids_up) {
+				$triggerids_up = array_intersect_key($triggerids_up, $tpl_triggerids_up);
+
+				if (!$triggerids_up) {
+					continue;
+				}
+
+				foreach ($trigger_links[$triggerid] as $hostid => $child_triggerid) {
+					$upd_child_triggerids_up = [];
+
+					if (array_key_exists($child_triggerid, $tpl_child_dependencies)) {
+						foreach ($tpl_child_dependencies[$child_triggerid] as $child_triggerid_up => $hostids_up) {
+							$hostid_up = key($hostids_up);
+							$triggerdepid = reset($hostids_up);
+
+							if (in_array($child_triggerid_up, $upd_child_triggerids_up)
+									|| in_array($triggerdepid, $del_triggerdepids)) {
+								continue;
+							}
+
+							foreach ($triggerids_up as $triggerid_up => $add) {
+								if (array_key_exists($hostid_up, $trigger_links[$triggerid_up])
+										&& bccomp($child_triggerid_up, $trigger_links[$triggerid_up][$hostid_up]) == 0) {
+									if ($add) {
+										$upd_child_triggerids_up[] = $child_triggerid_up;
+									}
+									else {
+										$del_triggerdepids[] = $hostids_up[$hostid_up];
+
+										$_edit_dependencies[$child_triggerid][$child_triggerid_up] = false;
+									}
+								}
+							}
+						}
+					}
+
+					foreach ($triggerids_up as $triggerid_up => $add) {
+						if ($add) {
+							$child_triggerid_up = $trigger_links[$triggerid_up][$hostid];
+
+							if (!in_array($child_triggerid_up, $upd_child_triggerids_up)) {
+								$_edit_dependencies[$child_triggerid][$child_triggerid_up] = true;
+							}
+						}
+					}
+				}
+			}
+		}
+
+		$host_triggerids_up = array_diff_key($all_triggerids_up, $tpl_triggerids_up);
+
+		if ($host_triggerids_up) {
+			if ($hostids === null) {
+				$result = DBselect(
+					'SELECT DISTINCT t.triggerid,td.triggerid_up,td.triggerdepid'.
+					' FROM triggers t,trigger_depends td'.
+					' WHERE t.triggerid=td.triggerid_down'.
+						' AND '.dbConditionId('t.templateid', array_keys($edit_dependencies)).
+						' AND '.dbConditionId('td.triggerid_up', array_keys($host_triggerids_up))
+				);
+			}
+			else {
+				$result = DBselect(
+					'SELECT DISTINCT t.triggerid,td.triggerid_up,td.triggerdepid'.
+					' FROM triggers t,functions f,items i,trigger_depends td'.
+					' WHERE t.triggerid=f.triggerid'.
+						' AND f.itemid=i.itemid'.
+						' AND t.triggerid=td.triggerid_down'.
+						' AND '.dbConditionId('t.templateid', array_keys($edit_dependencies)).
+						' AND '.dbConditionId('i.hostid', $hostids).
+						' AND '.dbConditionId('td.triggerid_up', array_keys($host_triggerids_up))
+				);
+			}
+
+			$host_child_dependencies = [];
+
+			while ($row = DBfetch($result)) {
+				$host_child_dependencies[$row['triggerid']][$row['triggerid_up']] = $row['triggerdepid'];
+			}
+
+			foreach ($edit_dependencies as $triggerid => $triggerids_up) {
+				$triggerids_up = array_intersect_key($triggerids_up, $host_triggerids_up);
+
+				if (!$triggerids_up) {
+					continue;
+				}
+
+				foreach ($trigger_links[$triggerid] as $hostid => $child_triggerid) {
+					$upd_child_triggerids_up = [];
+
+					if (array_key_exists($child_triggerid, $host_child_dependencies)) {
+						foreach ($host_child_dependencies[$child_triggerid] as $child_triggerid_up => $triggerdepid) {
+							if (array_key_exists($child_triggerid_up, $triggerids_up)) {
+								$add = $triggerids_up[$child_triggerid_up];
+
+								if ($add) {
+									$upd_child_triggerids_up[] = $child_triggerid_up;
+								}
+								else {
+									$del_triggerdepids[] = $triggerdepid;
+
+									$_edit_dependencies[$child_triggerid][$child_triggerid_up] = false;
+								}
+							}
+						}
+					}
+
+					foreach ($triggerids_up as $triggerid_up => $add) {
+						if ($add && !in_array($triggerid_up, $upd_child_triggerids_up)) {
+							$_edit_dependencies[$child_triggerid][$triggerid_up] = true;
+						}
+					}
+				}
+			}
+		}
+
+		$ins_dependencies = [];
+		$del_dependencies = [];
+		$ins_trigger_deps = [];
+
+		foreach ($_edit_dependencies as $triggerid => $triggerids_up) {
+			foreach ($triggerids_up as $triggerid_up => $add) {
+				if ($add) {
+					if ($trigger_flags[$triggerid] == ZBX_FLAG_DISCOVERY_PROTOTYPE) {
+						if ($trigger_flags[$triggerid_up] == ZBX_FLAG_DISCOVERY_PROTOTYPE) {
+							$ins_dependencies[$triggerid_up][$triggerid] = true;
+						}
+					}
+					else {
+						$ins_dependencies[$triggerid_up][$triggerid] = true;
+					}
+
+					$ins_trigger_deps[] = [
+						'triggerid_down' => $triggerid,
+						'triggerid_up' => $triggerid_up
+					];
+				}
+				else {
+					$del_dependencies[$triggerid_up][$triggerid] = true;
+				}
+			}
+		}
+
+		if ($ins_dependencies) {
+			self::checkCircularDependencies($ins_dependencies, $del_dependencies, true);
+		}
+
+		if ($del_triggerdepids) {
+			DB::delete('trigger_depends', ['triggerdepid' => $del_triggerdepids]);
+		}
+
+		if ($ins_trigger_deps) {
+			DB::insertBatch('trigger_depends', $ins_trigger_deps);
+		}
+
+		if ($_edit_dependencies) {
+			$_edit_dependencies = self::getTemplatedDependencies($_edit_dependencies);
+
+			if ($_edit_dependencies) {
+				self::inheritDependencies($_edit_dependencies);
+			}
+		}
+	}
+
+	/**
+	 * Inherit the trigger dependencies of the given templates to the given hosts.
+	 *
+	 * @param array $templateids
+	 * @param array $hostids
+	 */
+	public static function syncTemplateDependencies(array $templateids, array $hostids): void {
+		$result = DBselect(
+			'SELECT DISTINCT f.triggerid,td.triggerid_up'.
+			' FROM items i,functions f,trigger_depends td'.
+			' WHERE i.itemid=f.itemid'.
+				' AND f.triggerid=td.triggerid_down'.
+				' AND '.dbConditionId('i.hostid', $templateids)
+		);
+
+		$edit_dependencies = [];
+
+		while ($row = DBfetch($result)) {
+			$edit_dependencies[$row['triggerid']][$row['triggerid_up']] = true;
+		}
+
+		if ($edit_dependencies) {
+			$edit_dependencies = self::getTemplatedDependencies($edit_dependencies);
+
+			if ($edit_dependencies) {
+				self::inheritDependencies($edit_dependencies, $hostids);
+			}
+		}
+	}
 }
diff --git a/ui/include/classes/api/services/CTriggerPrototype.php b/ui/include/classes/api/services/CTriggerPrototype.php
index 3ffc3760604..3ccaa2db145 100644
--- a/ui/include/classes/api/services/CTriggerPrototype.php
+++ b/ui/include/classes/api/services/CTriggerPrototype.php
@@ -421,22 +421,13 @@ class CTriggerPrototype extends CTriggerGeneral {
 	 */
 	public function create(array $trigger_prototypes) {
 		$this->validateCreate($trigger_prototypes);
-		$this->createReal($trigger_prototypes);
-		$this->inherit($trigger_prototypes);
 
-		$addDependencies = false;
+		$this->createReal($trigger_prototypes);
+		$this->checkDependenciesLinks($trigger_prototypes);
 
-		foreach ($trigger_prototypes as $trigger_prototype) {
-			if (isset($trigger_prototype['dependencies']) && is_array($trigger_prototype['dependencies'])
-					&& $trigger_prototype['dependencies']) {
-				$addDependencies = true;
-				break;
-			}
-		}
+		$this->inherit($trigger_prototypes);
 
-		if ($addDependencies) {
-			$this->addDependencies($trigger_prototypes);
-		}
+		$this->updateDependencies($trigger_prototypes);
 
 		return ['triggerids' => zbx_objectValues($trigger_prototypes, 'triggerid')];
 	}
@@ -448,25 +439,15 @@ class CTriggerPrototype extends CTriggerGeneral {
 	 *
 	 * @return array
 	 */
-	public function update(array $trigger_prototypes) {
+	public function update(array $trigger_prototypes): array {
 		$this->validateUpdate($trigger_prototypes, $db_triggers);
+
 		$this->updateReal($trigger_prototypes, $db_triggers);
 		$this->inherit($trigger_prototypes);
 
-		$updateDependencies = false;
-
-		foreach ($trigger_prototypes as $trigger_prototype) {
-			if (isset($trigger_prototype['dependencies']) && is_array($trigger_prototype['dependencies'])) {
-				$updateDependencies = true;
-				break;
-			}
-		}
-
-		if ($updateDependencies) {
-			$this->updateDependencies($trigger_prototypes);
-		}
+		$this->updateDependencies($trigger_prototypes, $db_triggers);
 
-		return ['triggerids' => zbx_objectValues($trigger_prototypes, 'triggerid')];
+		return ['triggerids' => array_column($trigger_prototypes, 'triggerid')];
 	}
 
 	/**
@@ -529,539 +510,6 @@ class CTriggerPrototype extends CTriggerGeneral {
 	}
 
 	/**
-	 * Update the given dependencies and inherit them on all child triggers.
-	 *
-	 * @param array $triggerPrototypes
-	 */
-	protected function updateDependencies(array $triggerPrototypes) {
-		$this->deleteDependencies($triggerPrototypes);
-
-		$this->addDependencies($triggerPrototypes);
-	}
-
-	/**
-	 * Deletes all trigger and trigger prototype dependencies from the given trigger prototypes and their children.
-	 *
-	 * @param array  $triggerPrototypes
-	 * @param string $triggerPrototypes[]['triggerid']
-	 */
-	protected function deleteDependencies(array $triggerPrototypes) {
-		$triggerPrototypeIds = zbx_objectValues($triggerPrototypes, 'triggerid');
-
-		try {
-			// Delete the dependencies from the child trigger prototypes.
-
-			$childTriggerPrototypes = API::getApiService()->select($this->tableName(), [
-				'output' => ['triggerid'],
-				'filter' => [
-					'templateid' => $triggerPrototypeIds
-				]
-			]);
-
-			if ($childTriggerPrototypes) {
-				$this->deleteDependencies($childTriggerPrototypes);
-			}
-
-			DB::delete('trigger_depends', [
-				'triggerid_down' => $triggerPrototypeIds
-			]);
-		}
-		catch (APIException $e) {
-			self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot delete dependency'));
-		}
-	}
-
-	/**
-	 * Add the given dependencies and inherit them on all child triggers.
-	 *
-	 * @param array  $triggerPrototypes
-	 * @param string $triggerPrototypes[]['triggerid']
-	 * @param array  $triggerPrototypes[]['dependencies']
-	 * @param string $triggerPrototypes[]['dependencies'][]['triggerid']
-	 * @param bool   $inherited                                           Determines either to check permissions for
-	 *                                                                    added dependencies. Permissions are not
-	 *                                                                    validated for inherited triggers.
-	 */
-	public function addDependencies(array $triggerPrototypes, bool $inherited = false) {
-		$this->validateAddDependencies($triggerPrototypes, $inherited);
-
-		$insert = [];
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			if (!array_key_exists('dependencies', $triggerPrototype)) {
-				continue;
-			}
-
-			foreach ($triggerPrototype['dependencies'] as $dependency) {
-				$insert[] = [
-					'triggerid_down' => $triggerPrototype['triggerid'],
-					'triggerid_up' => $dependency['triggerid']
-				];
-			}
-		}
-
-		DB::insertBatch('trigger_depends', $insert);
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			// Propagate the dependencies to the child triggers.
-
-			$childTriggers = API::getApiService()->select($this->tableName(), [
-				'output' => ['triggerid'],
-				'filter' => [
-					'templateid' => $triggerPrototype['triggerid']
-				]
-			]);
-
-			if ($childTriggers) {
-				foreach ($childTriggers as &$childTrigger) {
-					$childTrigger['dependencies'] = [];
-					$childHostsQuery = get_hosts_by_triggerid($childTrigger['triggerid']);
-
-					while ($childHost = DBfetch($childHostsQuery)) {
-						foreach ($triggerPrototype['dependencies'] as $dependency) {
-							$newDependency = [$childTrigger['triggerid'] => $dependency['triggerid']];
-							$newDependency = replace_template_dependencies($newDependency, $childHost['hostid']);
-
-							$childTrigger['dependencies'][] = [
-								'triggerid' => $newDependency[$childTrigger['triggerid']]
-							];
-						}
-					}
-				}
-				unset($childTrigger);
-
-				$this->addDependencies($childTriggers, true);
-			}
-		}
-	}
-
-	/**
-	 * Validates the input for the addDependencies() method.
-	 *
-	 * @param array  $trigger_prototypes
-	 * @param string $trigger_prototypes[]['triggerid']
-	 * @param array  $trigger_prototypes[]['dependencies']
-	 * @param string $trigger_prototypes[]['dependencies'][]['triggerid']
-	 * @param bool   $inherited
-	 *
-	 * @throws APIException if the given dependencies are invalid.
-	 */
-	protected function validateAddDependencies(array $trigger_prototypes, bool $inherited = false): void {
-		$depTriggerIds = [];
-
-		foreach ($trigger_prototypes as $trigger_prototype) {
-			if (!array_key_exists('dependencies', $trigger_prototype)) {
-				continue;
-			}
-
-			foreach ($trigger_prototype['dependencies'] as $dependency) {
-				$depTriggerIds[$dependency['triggerid']] = $dependency['triggerid'];
-			}
-		}
-
-		if (!$depTriggerIds) {
-			return;
-		}
-
-		// Check if given IDs are actual trigger prototypes and get discovery rules if they are.
-		$depTriggerPrototypes = $this->get([
-			'output' => ['triggerid'],
-			'selectDiscoveryRule' => ['itemid'],
-			'triggerids' => $depTriggerIds,
-			'nopermissions' => $inherited ? true : null,
-			'preservekeys' => true
-		]);
-
-		$dep_triggerids = array_diff($depTriggerIds, array_keys($depTriggerPrototypes));
-
-		if ($depTriggerPrototypes) {
-			// Get current trigger prototype discovery rules.
-			$dRules = $this->get([
-				'output' => ['triggerid'],
-				'selectDiscoveryRule' => ['itemid'],
-				'triggerids' => zbx_objectValues($trigger_prototypes, 'triggerid'),
-				'nopermissions' => $inherited ? true : null,
-				'preservekeys' => true
-			]);
-
-			foreach ($trigger_prototypes as $trigger_prototype) {
-				if (!array_key_exists('dependencies', $trigger_prototype)) {
-					continue;
-				}
-
-				$dRuleId = $dRules[$trigger_prototype['triggerid']]['discoveryRule']['itemid'];
-
-				// Check if current trigger prototype rules match dependent trigger prototype rules.
-				foreach ($trigger_prototype['dependencies'] as $dependency) {
-					if (isset($depTriggerPrototypes[$dependency['triggerid']])) {
-						$depTriggerDRuleId = $depTriggerPrototypes[$dependency['triggerid']]['discoveryRule']['itemid'];
-
-						if (bccomp($depTriggerDRuleId, $dRuleId) != 0) {
-							self::exception(ZBX_API_ERROR_PERMISSIONS,
-								_('No permissions to referred object or it does not exist!')
-							);
-						}
-					}
-				}
-			}
-		}
-		elseif (!$dep_triggerids) {
-			self::exception(ZBX_API_ERROR_PERMISSIONS, _('No permissions to referred object or it does not exist!'));
-		}
-
-		if ($dep_triggerids && !$inherited) {
-			// Check other dependency IDs if those are normal triggers.
-			$count = API::Trigger()->get([
-				'countOutput' => true,
-				'triggerids' => $dep_triggerids,
-				'filter' => [
-					'flags' => [ZBX_FLAG_DISCOVERY_NORMAL]
-				]
-			]);
-
-			if ($count != count($dep_triggerids)) {
-				self::exception(ZBX_API_ERROR_PERMISSIONS,
-					_('No permissions to referred object or it does not exist!')
-				);
-			}
-		}
-
-		$this->checkDependencies($trigger_prototypes);
-		$this->checkDependencyParents($trigger_prototypes);
-		$this->checkDependencyDuplicates($trigger_prototypes);
-	}
-
-	/**
-	 * Check the dependencies of the given trigger prototypes.
-	 *
-	 * @param array  $triggerPrototypes
-	 * @param string $triggerPrototypes[]['triggerid']
-	 * @param array  $triggerPrototypes[]['dependencies']
-	 * @param string $triggerPrototypes[]['dependencies'][]['triggerid']
-	 *
-	 * @throws APIException if any of the dependencies are invalid.
-	 */
-	protected function checkDependencies(array $triggerPrototypes) {
-		$triggerPrototypes = zbx_toHash($triggerPrototypes, 'triggerid');
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			if (!array_key_exists('dependencies', $triggerPrototype)) {
-				continue;
-			}
-
-			$triggerid_down = $triggerPrototype['triggerid'];
-			$triggerids_up = zbx_objectValues($triggerPrototype['dependencies'], 'triggerid');
-
-			foreach ($triggerids_up as $triggerid_up) {
-				if (bccomp($triggerid_down, $triggerid_up) == 0) {
-					self::exception(ZBX_API_ERROR_PARAMETERS,
-						_('Cannot create dependency on trigger prototype itself.')
-					);
-				}
-			}
-		}
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			if (!array_key_exists('dependencies', $triggerPrototype)) {
-				continue;
-			}
-
-			$depTriggerIds = zbx_objectValues($triggerPrototype['dependencies'], 'triggerid');
-
-			$triggerTemplates = API::Template()->get([
-				'output' => ['hostid', 'status'],
-				'triggerids' => [$triggerPrototype['triggerid']],
-				'nopermissions' => true
-			]);
-
-			if (!$triggerTemplates) {
-				// Current trigger prototype belongs to a host, so forbid dependencies from a host to a template.
-
-				$triggerDepTemplates = API::Template()->get([
-					'output' => ['templateid'],
-					'triggerids' => $depTriggerIds,
-					'nopermissions' => true,
-					'limit' => 1
-				]);
-
-				if ($triggerDepTemplates) {
-					self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot add dependency from a host to a template.'));
-				}
-			}
-
-			// check circular dependency
-			$downTriggerIds = [$triggerPrototype['triggerid']];
-			do {
-				// triggerid_down depends on triggerid_up
-				$res = DBselect(
-					'SELECT td.triggerid_up'.
-					' FROM trigger_depends td'.
-					' WHERE '.dbConditionInt('td.triggerid_down', $downTriggerIds)
-				);
-
-				// combine db dependencies with those to be added
-				$upTriggersIds = [];
-				while ($row = DBfetch($res)) {
-					$upTriggersIds[] = $row['triggerid_up'];
-				}
-				foreach ($downTriggerIds as $id) {
-					if (isset($triggerPrototypes[$id]) && isset($triggerPrototypes[$id]['dependencies'])) {
-						$upTriggersIds = array_merge($upTriggersIds,
-							zbx_objectValues($triggerPrototypes[$id]['dependencies'], 'triggerid')
-						);
-					}
-				}
-
-				// if found trigger id is in dependent triggerids, there is a dependency loop
-				$downTriggerIds = [];
-				foreach ($upTriggersIds as $id) {
-					if (bccomp($id, $triggerPrototype['triggerid']) == 0) {
-						self::exception(ZBX_API_ERROR_PARAMETERS, _('Cannot create circular dependencies.'));
-					}
-					$downTriggerIds[] = $id;
-				}
-			} while (!empty($downTriggerIds));
-
-			// fetch all templates that are used in dependencies
-			$triggerDepTemplates = API::Template()->get([
-				'output' => ['templateid'],
-				'triggerids' => $depTriggerIds,
-				'nopermissions' => true,
-				'preservekeys' => true
-			]);
-
-			$depTemplateIds = array_keys($triggerDepTemplates);
-
-			// run the check only if a templated trigger has dependencies on other templates
-			$triggerTemplateIds = zbx_toHash(zbx_objectValues($triggerTemplates, 'templateid'));
-			$tdiff = array_diff($depTemplateIds, $triggerTemplateIds);
-
-			if (!empty($triggerTemplateIds) && !empty($depTemplateIds) && !empty($tdiff)) {
-				$affectedTemplateIds = zbx_array_merge($triggerTemplateIds, $depTemplateIds);
-
-				// create a list of all hosts, that are children of the affected templates
-				$dbLowlvltpl = DBselect(
-					'SELECT DISTINCT ht.templateid,ht.hostid,h.host'.
-					' FROM hosts_templates ht,hosts h'.
-					' WHERE h.hostid=ht.hostid'.
-						' AND '.dbConditionInt('ht.templateid', $affectedTemplateIds)
-				);
-				$map = [];
-				while ($lowlvltpl = DBfetch($dbLowlvltpl)) {
-					if (!isset($map[$lowlvltpl['hostid']])) {
-						$map[$lowlvltpl['hostid']] = [];
-					}
-					$map[$lowlvltpl['hostid']][$lowlvltpl['templateid']] = $lowlvltpl['host'];
-				}
-
-				// check that if some host is linked to the template, that the trigger belongs to,
-				// the host must also be linked to all of the templates, that trigger dependencies point to
-				foreach ($map as $templates) {
-					foreach ($triggerTemplateIds as $triggerTemplateId) {
-						// is the host linked to one of the trigger templates?
-						if (isset($templates[$triggerTemplateId])) {
-							// then make sure all of the dependency templates are also linked
-							foreach ($depTemplateIds as $depTemplateId) {
-								if (!isset($templates[$depTemplateId])) {
-									self::exception(ZBX_API_ERROR_PARAMETERS,
-										_s('Not all templates are linked to "%1$s".', reset($templates))
-									);
-								}
-							}
-							break;
-						}
-					}
-				}
-			}
-		}
-	}
-
-	/**
-	 * Check that none of the triggers have dependencies on their children. Checks only one level of inheritance, but
-	 * since it is called on each inheritance step, also works for multiple inheritance levels.
-	 *
-	 * @param array  $triggerPrototypes
-	 * @param string $triggerPrototypes[]['triggerid']
-	 * @param array  $triggerPrototypes[]['dependencies']
-	 * @param string $triggerPrototypes[]['dependencies'][]['triggerid']
-	 *
-	 * @throws APIException if at least one trigger is dependent on its child.
-	 */
-	protected function checkDependencyParents(array $triggerPrototypes) {
-		// fetch all templated dependency trigger parents
-		$depTriggerIds = [];
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			if (!array_key_exists('dependencies', $triggerPrototype)) {
-				continue;
-			}
-
-			foreach ($triggerPrototype['dependencies'] as $dependency) {
-				$depTriggerIds[$dependency['triggerid']] = $dependency['triggerid'];
-			}
-		}
-
-		$parentDepTriggers = DBfetchArray(DBSelect(
-			'SELECT templateid,triggerid'.
-			' FROM triggers'.
-			' WHERE templateid>0'.
-				' AND '.dbConditionInt('triggerid', $depTriggerIds)
-		));
-
-		if ($parentDepTriggers) {
-			$parentDepTriggers = zbx_toHash($parentDepTriggers, 'triggerid');
-
-			foreach ($triggerPrototypes as $triggerPrototype) {
-				foreach ($triggerPrototype['dependencies'] as $dependency) {
-					// Check if the current trigger is the parent of the dependency trigger.
-
-					$depTriggerId = $dependency['triggerid'];
-
-					if (isset($parentDepTriggers[$depTriggerId])
-							&& $parentDepTriggers[$depTriggerId]['templateid'] == $triggerPrototype['triggerid']) {
-
-						self::exception(ZBX_API_ERROR_PARAMETERS,
-							_s('Trigger prototype cannot be dependent on a trigger that is inherited from it.')
-						);
-					}
-				}
-			}
-		}
-	}
-
-	/**
-	 * Checks if the given dependencies contain duplicates.
-	 *
-	 * @param array  $triggerPrototypes
-	 * @param string $triggerPrototypes[]['triggerid']
-	 * @param array  $triggerPrototypes[]['dependencies']
-	 * @param string $triggerPrototypes[]['dependencies'][]['triggerid']
-	 *
-	 * @throws APIException if the given dependencies contain duplicates.
-	 */
-	protected function checkDependencyDuplicates(array $triggerPrototypes) {
-		// check duplicates in array
-		$uniqueTriggers = [];
-		$depTriggerIds = [];
-		$duplicateTriggerId = null;
-
-		foreach ($triggerPrototypes as $triggerPrototype) {
-			if (!array_key_exists('dependencies', $triggerPrototype)) {
-				continue;
-			}
-
-			foreach ($triggerPrototype['dependencies'] as $dependency) {
-				$depTriggerIds[$dependency['triggerid']] = $dependency['triggerid'];
-
-				if (isset($uniqueTriggers[$triggerPrototype['triggerid']][$dependency['triggerid']])) {
-					$duplicateTriggerId = $triggerPrototype['triggerid'];
-					break 2;
-				}
-				else {
-					$uniqueTriggers[$triggerPrototype['triggerid']][$dependency['triggerid']] = 1;
-				}
-			}
-		}
-
-		if ($duplicateTriggerId === null) {
-			// check if dependency already exists in DB
-			foreach ($triggerPrototypes as $triggerPrototype) {
-				$dbUpTriggers = DBselect(
-					'SELECT td.triggerid_up'.
-					' FROM trigger_depends td'.
-					' WHERE '.dbConditionInt('td.triggerid_up', $depTriggerIds).
-					' AND td.triggerid_down='.zbx_dbstr($triggerPrototype['triggerid'])
-				, 1);
-				if (DBfetch($dbUpTriggers)) {
-					$duplicateTriggerId = $triggerPrototype['triggerid'];
-					break;
-				}
-			}
-		}
-
-		if ($duplicateTriggerId) {
-			$duplicateTrigger = DBfetch(DBselect(
-				'SELECT t.description'.
-				' FROM triggers t'.
-				' WHERE t.triggerid='.zbx_dbstr($duplicateTriggerId)
-			));
-			self::exception(ZBX_API_ERROR_PARAMETERS,
-				_s('Duplicate dependencies in trigger prototype "%1$s".', $duplicateTrigger['description'])
-			);
-		}
-	}
-
-	/**
-	 * Synchronizes the templated trigger prototype dependencies on the given hosts inherited from the given templates.
-	 * Update dependencies, do it after all triggers and trigger prototypes that can be dependent were created/updated
-	 * on all child hosts/templates. Starting from highest level template trigger prototypes select trigger prototypes
-	 * from one level lower, then for each lower trigger prototype look if it's parent has dependencies, if so
-	 * find this dependency trigger prototype child on dependent trigger prototype host and add new dependency.
-	 *
-	 * @param array			$data
-	 * @param array|string	$data['templateids']
-	 * @param array|string	$data['hostids']
-	 */
-	public function syncTemplateDependencies(array $data) {
-		$templateIds = zbx_toArray($data['templateids']);
-		$hostIds = zbx_toArray($data['hostids']);
-
-		$parentTriggers = $this->get([
-			'output' => ['triggerid'],
-			'selectDependencies' => ['triggerid'],
-			'hostids' => $templateIds,
-			'preservekeys' => true,
-			'nopermissions' => true
-		]);
-
-		if ($parentTriggers) {
-			$childTriggers = $this->get([
-				'output' => ['triggerid', 'templateid'],
-				'selectHosts' => ['hostid'],
-				'hostids' => ($hostIds) ? $hostIds : null,
-				'filter' => ['templateid' => array_keys($parentTriggers)],
-				'nopermissions' => true,
-				'preservekeys' => true
-			]);
-
-			if ($childTriggers) {
-				$newDependencies = [];
-
-				foreach ($childTriggers as $childTrigger) {
-					$parentDependencies = $parentTriggers[$childTrigger['templateid']]['dependencies'];
-
-					if ($parentDependencies) {
-						$newDependencies[$childTrigger['triggerid']] = [
-							'triggerid' => $childTrigger['triggerid'],
-							'dependencies' => []
-						];
-
-						$dependencies = [];
-						foreach ($parentDependencies as $depTrigger) {
-							$dependencies[] = $depTrigger['triggerid'];
-						}
-
-						$host = reset($childTrigger['hosts']);
-						$dependencies = replace_template_dependencies($dependencies, $host['hostid']);
-
-						foreach ($dependencies as $depTriggerId) {
-							$newDependencies[$childTrigger['triggerid']]['dependencies'][] = [
-								'triggerid' => $depTriggerId
-							];
-						}
-					}
-				}
-
-				$this->deleteDependencies($childTriggers, true);
-
-				if ($newDependencies) {
-					$this->addDependencies($newDependencies, true);
-				}
-			}
-		}
-	}
-
-	/**
 	 * Retrieves and adds additional requested data (options 'selectHosts', 'selectGroups', etc.) to result set.
 	 *
 	 * @param array		$options
diff --git a/ui/include/forms.inc.php b/ui/include/forms.inc.php
index 2075ce4e3a3..0c194700f7d 100644
--- a/ui/include/forms.inc.php
+++ b/ui/include/forms.inc.php
@@ -1573,9 +1573,16 @@ function getCopyElementsFormData($elements_field, $title = null) {
 		'elements' => getRequest($elements_field, []),
 		'copy_type' => getRequest('copy_type', COPY_TYPE_TO_HOST_GROUP),
 		'copy_targetids' => getRequest('copy_targetids', []),
-		'hostid' => getRequest('hostid', 0)
+		'hostid' => 0
 	];
 
+	$prefix = (getRequest('context') === 'host') ? 'web.hosts.' : 'web.templates.';
+	$filter_hostids = getRequest('filter_hostids', CProfile::getArray($prefix.'triggers.filter_hostids', []));
+
+	if (count($filter_hostids) == 1) {
+		$data['hostid'] = reset($filter_hostids);
+	}
+
 	if (!$data['elements'] || !is_array($data['elements'])) {
 		show_error_message(_('Incorrect list of items.'));
 
diff --git a/ui/include/triggers.inc.php b/ui/include/triggers.inc.php
index 2bdd76b93ad..bbd85dc35f5 100644
--- a/ui/include/triggers.inc.php
+++ b/ui/include/triggers.inc.php
@@ -93,18 +93,6 @@ function get_trigger_by_triggerid($triggerid) {
 	return false;
 }
 
-function get_hosts_by_triggerid($triggerids) {
-	zbx_value2array($triggerids);
-
-	return DBselect(
-		'SELECT DISTINCT h.*'.
-		' FROM hosts h,functions f,items i'.
-		' WHERE i.itemid=f.itemid'.
-			' AND h.hostid=i.hostid'.
-			' AND '.dbConditionInt('f.triggerid', $triggerids)
-	);
-}
-
 function get_triggers_by_hostid($hostid) {
 	return DBselect(
 		'SELECT DISTINCT t.*'.
@@ -148,27 +136,68 @@ function utf8RawUrlDecode($source) {
 }
 
 /**
- * Copies the given triggers to the given hosts or templates.
- *
- * Without the $src_hostid parameter it will only be able to copy triggers that belong to only one host. If the
- * $src_hostid parameter is not passed, and a trigger has multiple hosts, it will throw an error. If the
- * $src_hostid parameter is passed, the given host will be replaced with the destination host.
+ * Copy the given triggers to the target hosts or templates, taking care of copied trigger dependencies.
  *
- * This function takes care of copied trigger dependencies.
- * If trigger is copied alongside with trigger on which it depends, then dependencies is replaced directly using new ids,
- * If there is target host within dependency trigger, algorithm will search for potential matching trigger in target host,
- * if matching trigger is found, then id from this trigger is used, if not rise exception,
- * otherwise original dependency will be left.
+ * If the $src_hostid parameter is passed, the given host will be replaced with the destination host.
+ * Without $src_hostid, only triggers that belong to a single host or template can be copied.
  *
+ * If a trigger is copied alongside with the trigger which it depends on, then dependencies are replaced directly,
+ * using new IDs.
+ * If the source trigger depends on the trigger from the same host or template, the same trigger-up should exist on the
+ * target host or template.
  *
- * @param array $src_triggerids		Triggers which will be copied to $dst_hostids
- * @param array $dst_hostids		Hosts and templates to whom add triggers. IDs not present in DB (host table)
- *									will be ignored.
- * @param int	$src_hostid			Host ID in which context trigger with multiple hosts will be treated.
+ * @param array       $dst_hostids     Hosts and templates to copy triggers to.
+ *                                     IDs not present in the database will be ignored.
+ * @param string|null $src_hostid      ID of host to use as context for trigger when multiple hosts are involved.
+ * @param array|null  $src_triggerids  Triggers which will be copied to destination host(s).
  *
  * @return bool
  */
-function copyTriggersToHosts($src_triggerids, $dst_hostids, $src_hostid = null) {
+function copyTriggersToHosts(array $dst_hostids, ?string $src_hostid, array $src_triggerids = null): bool {
+	$dst_templates = API::Template()->get([
+		'output' => ['host'],
+		'templateids' => $dst_hostids,
+		'editable' => true,
+		'preservekeys' => true
+	]);
+
+	$_dst_hostids = array_diff($dst_hostids, array_keys($dst_templates));
+
+	$dst_hosts = $_dst_hostids
+		?  API::Host()->get([
+			'output' => ['host', 'status'],
+			'hostids' => $_dst_hostids,
+			'editable' => true,
+			'preservekeys' => true
+		])
+		: [];
+
+	$dst_hosts = $dst_templates + $dst_hosts;
+
+	if (!$dst_hosts || count($dst_hosts) != count($dst_hostids)) {
+		return false;
+	}
+
+	if ($src_hostid) {
+		$src_hosts = API::Template()->get([
+			'output' => ['host'],
+			'templateids' => $src_hostid
+		]);
+
+		$src_hosts = $src_hosts
+			? $src_hosts
+			: API::Host()->get([
+				'output' => ['host'],
+				'hostids' => $src_hostid
+			]);
+
+		if (!$src_hosts) {
+			return false;
+		}
+
+		$src_host = $src_hosts[0]['host'];
+	}
+
 	$options = [
 		'output' => ['triggerid', 'expression', 'description', 'url', 'status', 'priority', 'comments', 'type',
 			'recovery_mode', 'recovery_expression', 'correlation_mode', 'correlation_tag', 'manual_close', 'opdata',
@@ -176,225 +205,249 @@ function copyTriggersToHosts($src_triggerids, $dst_hostids, $src_hostid = null)
 		],
 		'selectDependencies' => ['triggerid'],
 		'selectTags' => ['tag', 'value'],
-		'triggerids' => $src_triggerids
+		'preservekeys' => true
 	];
 
-	if ($src_hostid) {
-		$srcHost = API::Host()->get([
-			'output' => ['host'],
+	if (!$src_hostid) {
+		$options += ['selectHosts' => ['hostid', 'host']];
+	}
+
+	if ($src_triggerids) {
+		$options += ['triggerids' => $src_triggerids];
+	}
+	else {
+		$options += [
 			'hostids' => $src_hostid,
-			'preservekeys' => true,
-			'templated_hosts' => true
-		]);
+			'inherited' => false,
+			'filter' => ['flags' => ZBX_FLAG_DISCOVERY_NORMAL]
+		];
+	}
 
-		if (!$srcHost = reset($srcHost)) {
+	$src_triggers = API::Trigger()->get($options);
+
+	if ($src_triggerids) {
+		if (count($src_triggers) != count($src_triggerids)) {
 			return false;
 		}
 	}
 	else {
-		// Select source trigger first host 'host'.
-		$options['selectHosts'] = ['host'];
+		if (!$src_triggers) {
+			return true;
+		}
 	}
 
-	$dbSrcTriggers = API::Trigger()->get($options);
-
-	$dbSrcTriggers = CMacrosResolverHelper::resolveTriggerExpressions($dbSrcTriggers,
+	$src_triggers = CMacrosResolverHelper::resolveTriggerExpressions($src_triggers,
 		['sources' => ['expression', 'recovery_expression']]
 	);
 
-	$dbDstHosts = API::Host()->get([
-		'output' => ['hostid', 'host'],
-		'hostids' => $dst_hostids,
-		'preservekeys' => true,
-		'templated_hosts' => true
-	]);
+	if (!$src_hostid) {
+		foreach ($src_triggers as $src_trigger) {
+			if (count($src_trigger['hosts']) > 1) {
+				error(_s('Cannot copy trigger "%1$s", because it has multiple hosts in the expression.',
+					$src_trigger['description']
+				));
+
+				return false;
+			}
+		}
+	}
 
-	$newTriggers = [];
+	$dst_triggers = [];
+	$trigger_links = [];
+	$i = 0;
 
-	foreach ($dbDstHosts as $dstHost) {
-		// Create each trigger for each host.
+	foreach ($dst_hosts as $dst_hostid => $dst_host) {
+		foreach ($src_triggers as $src_triggerid => $src_trigger) {
+			$dst_trigger = array_intersect_key($src_trigger, array_flip(['expression', 'description', 'url', 'status',
+				'priority', 'comments', 'type', 'recovery_mode', 'recovery_expression', 'correlation_mode',
+				'correlation_tag', 'manual_close', 'opdata', 'event_name', 'tags'
+			]));
 
-		foreach ($dbSrcTriggers as $srcTrigger) {
-			if ($src_hostid) {
-				// Get host 'host' for triggerExpressionReplaceHost().
+			$_src_host = $src_hostid ? $src_host : $src_trigger['hosts'][0]['host'];
 
-				$host = $srcHost['host'];
-				$srcTriggerContextHostId = $src_hostid;
+			$dst_trigger['expression'] =
+				triggerExpressionReplaceHost($src_trigger['expression'], $_src_host, $dst_host['host']);
+
+			if ($src_trigger['recovery_mode'] == ZBX_RECOVERY_MODE_RECOVERY_EXPRESSION) {
+				$dst_trigger['recovery_expression'] =
+					triggerExpressionReplaceHost($src_trigger['recovery_expression'], $_src_host, $dst_host['host']);
 			}
-			else {
-				if (count($srcTrigger['hosts']) > 1) {
-					error(_s('Cannot copy trigger "%1$s:%2$s", because it has multiple hosts in the expression.',
-						$srcTrigger['description'], $srcTrigger['expression']
-					));
 
-					return false;
-				}
+			$dst_triggers[] = $dst_trigger;
+			$trigger_links[$src_triggerid][$dst_hostid] = $i;
 
-				// Use source trigger first host 'host'.
-				$host = $srcTrigger['hosts'][0]['host'];
-				$srcTriggerContextHostId = $srcTrigger['hosts'][0]['hostid'];
-			}
+			$i++;
+		}
+	}
 
-			$srcTrigger['expression'] = triggerExpressionReplaceHost($srcTrigger['expression'], $host,
-				$dstHost['host']
-			);
+	$result = API::Trigger()->create($dst_triggers);
 
-			if ($srcTrigger['recovery_mode'] == ZBX_RECOVERY_MODE_RECOVERY_EXPRESSION) {
-				$srcTrigger['recovery_expression'] = triggerExpressionReplaceHost($srcTrigger['recovery_expression'],
-					$host, $dstHost['host']
-				);
-			}
+	if (!$result) {
+		return false;
+	}
 
-			// The dependencies must be added after all triggers are created.
-			$result = API::Trigger()->create([[
-				'description' => $srcTrigger['description'],
-				'event_name' => $srcTrigger['event_name'],
-				'opdata' => $srcTrigger['opdata'],
-				'expression' => $srcTrigger['expression'],
-				'url' => $srcTrigger['url'],
-				'status' => $srcTrigger['status'],
-				'priority' => $srcTrigger['priority'],
-				'comments' => $srcTrigger['comments'],
-				'type' => $srcTrigger['type'],
-				'recovery_mode' => $srcTrigger['recovery_mode'],
-				'recovery_expression' => $srcTrigger['recovery_expression'],
-				'correlation_mode' => $srcTrigger['correlation_mode'],
-				'correlation_tag' => $srcTrigger['correlation_tag'],
-				'tags' => $srcTrigger['tags'],
-				'manual_close' => $srcTrigger['manual_close']
-			]]);
-
-			if (!$result) {
-				return false;
+	$dst_triggerids = $result['triggerids'];
+
+	$dst_triggers = [];
+	$src_triggerids_up = [];
+
+	foreach ($trigger_links as $src_triggerid => $links) {
+		foreach ($links as $dst_hostid => $i) {
+			if (!$src_triggers[$src_triggerid]['dependencies']) {
+				continue;
 			}
 
-			$newTriggers[$srcTrigger['triggerid']][] = [
-				'newTriggerId' => reset($result['triggerids']),
-				'newTriggerExpression' => $srcTrigger['expression'],
-				'newTriggerHostId' => $dstHost['hostid'],
-				'newTriggerHost' => $dstHost['host'],
-				'srcTriggerContextHostId' => $srcTriggerContextHostId,
-				'srcTriggerContextHost' => $host
-			];
+			$dst_triggers[$i] = ['triggerid' => $dst_triggerids[$i]];
+
+			foreach ($src_triggers[$src_triggerid]['dependencies'] as $src_trigger_up) {
+				if (array_key_exists($src_trigger_up['triggerid'], $trigger_links)) {
+					$dst_triggers[$i]['dependencies'][] = [
+						'triggerid' => $dst_triggerids[$trigger_links[$src_trigger_up['triggerid']][$dst_hostid]]
+					];
+				}
+				elseif ($src_triggerids) {
+					$src_triggerids_up[$src_trigger_up['triggerid']] = true;
+				}
+				else {
+					$dst_triggers[$i]['dependencies'][] = ['triggerid' => $src_trigger_up['triggerid']];
+				}
+			}
 		}
 	}
 
-	$depids = [];
-	foreach ($dbSrcTriggers as $srcTrigger) {
-		foreach ($srcTrigger['dependencies'] as $depTrigger) {
-			$depids[] = $depTrigger['triggerid'];
+	if ($src_triggerids_up) {
+		$src_triggers_up = API::Trigger()->get([
+			'output' => ['description', 'expression', 'recovery_mode', 'recovery_expression'],
+			'selectHosts' => ['hostid'],
+			'triggerids' => array_keys($src_triggerids_up),
+			'preservekeys' => true
+		]);
+
+		$src_triggers_up = CMacrosResolverHelper::resolveTriggerExpressions($src_triggers_up,
+			['sources' => ['expression', 'recovery_expression']]
+		);
+
+		$src_host_dependencies = [];
+
+		foreach ($trigger_links as $src_triggerid => $links) {
+			$_src_hostid = $src_hostid ? $src_hostid : $src_triggers[$src_triggerid]['hosts'][0]['hostid'];
+
+			foreach ($links as $dst_hostid => $i) {
+				foreach ($src_triggers[$src_triggerid]['dependencies'] as $src_trigger_up) {
+					if (!array_key_exists($src_trigger_up['triggerid'], $src_triggers_up)) {
+						continue;
+					}
+
+					$src_hostids_up = array_column($src_triggers_up[$src_trigger_up['triggerid']]['hosts'], 'hostid');
+
+					if (in_array($_src_hostid, $src_hostids_up)) {
+						$src_host_dependencies[$src_trigger_up['triggerid']][$src_triggerid] = true;
+					}
+					else {
+						$dst_triggers[$i]['dependencies'][] = ['triggerid' => $src_trigger_up['triggerid']];
+					}
+				}
+			}
 		}
-	}
-	$depTriggers = API::Trigger()->get([
-		'triggerids' => $depids,
-		'output' => ['description', 'expression', 'recovery_mode', 'recovery_expression'],
-		'selectHosts' => ['hostid'],
-		'preservekeys' => true
-	]);
 
-	$depTriggers = CMacrosResolverHelper::resolveTriggerExpressions($depTriggers,
-		['sources' => ['expression', 'recovery_expression']]
-	);
+		if ($src_host_dependencies) {
+			$descriptions = array_unique(array_column(array_intersect_key($src_triggers_up, $src_host_dependencies),
+				'description'
+			));
 
-	if ($newTriggers) {
-		// Map dependencies to the new trigger IDs and save.
-
-		$dependencies = [];
-
-		foreach ($dbSrcTriggers as $srcTrigger) {
-			if ($srcTrigger['dependencies']) {
-				// Get corresponding created triggers.
-				$dst_triggers = $newTriggers[$srcTrigger['triggerid']];
-
-				foreach ($dst_triggers as $dst_trigger) {
-					foreach ($srcTrigger['dependencies'] as $depTrigger) {
-						/*
-						 * We have added $depTrigger trigger and we know corresponding trigger ID for newly
-						 * created trigger.
-						 */
-						if (array_key_exists($depTrigger['triggerid'], $newTriggers)) {
-							$dst_dep_triggers = $newTriggers[$depTrigger['triggerid']];
-
-							foreach ($dst_dep_triggers as $dst_dep_trigger) {
-								/*
-								 * Dependency is within same host according to $src_hostid parameter or dep trigger has
-								 * single host.
-								 */
-								if ($dst_trigger['srcTriggerContextHostId'] == $dst_dep_trigger['srcTriggerContextHostId']
-										&& $dst_dep_trigger['newTriggerHostId'] == $dst_trigger['newTriggerHostId']) {
-									$depTriggerId = $dst_dep_trigger['newTriggerId'];
-									break;
-								}
-								// Dependency is to trigger from another host.
-								else {
-									$depTriggerId = $depTrigger['triggerid'];
-								}
-							}
-						}
-						// We need to search for $depTrigger trigger if target host is within dependency hosts.
-						elseif (in_array(['hostid' => $dst_trigger['srcTriggerContextHostId']],
-								$depTriggers[$depTrigger['triggerid']]['hosts'])) {
-							// Get all possible $depTrigger matching triggers by description.
-							$targetHostTriggersByDescription = API::Trigger()->get([
-								'hostids' => $dst_trigger['newTriggerHostId'],
-								'output' => ['hosts', 'triggerid', 'expression'],
-								'filter' => ['description' => $depTriggers[$depTrigger['triggerid']]['description']],
-								'preservekeys' => true
-							]);
-
-							$targetHostTriggersByDescription =
-								CMacrosResolverHelper::resolveTriggerExpressions($targetHostTriggersByDescription);
-
-							// Compare exploded expressions for exact match.
-							$expr1 = $depTriggers[$depTrigger['triggerid']]['expression'];
-							$depTriggerId = null;
-
-							foreach ($targetHostTriggersByDescription as $potentialTargetTrigger) {
-								$expr2 = triggerExpressionReplaceHost($potentialTargetTrigger['expression'],
-									$dst_trigger['newTriggerHost'], $dst_trigger['srcTriggerContextHost']
-								);
-
-								if ($expr2 == $expr1) {
-									// Matching trigger has been found.
-									$depTriggerId = $potentialTargetTrigger['triggerid'];
-									break;
-								}
-							}
+			$dst_host_triggers = API::Trigger()->get([
+				'output' => ['triggerid', 'description', 'expression', 'recovery_expression'],
+				'selectHosts' => ['hostid'],
+				'hostids' => array_keys($dst_hosts),
+				'filter' => ['description' => $descriptions],
+				'preservekeys' => true
+			]);
 
-							// If matching trigger wasn't found raise exception.
-							if ($depTriggerId === null) {
-								$expr2 = triggerExpressionReplaceHost($expr1, $dst_trigger['srcTriggerContextHost'],
-									$dst_trigger['newTriggerHost']
-								);
+			if (!$dst_host_triggers) {
+				$src_triggerid_up = key($src_host_dependencies);
+				$src_triggerid = key($src_host_dependencies[$src_triggerid_up]);
+				$dst_hostid = key($trigger_links[$src_triggerid]);
 
-								error(_s(
-									'Cannot add dependency from trigger "%1$s:%2$s" to non existing trigger "%3$s:%4$s".',
-									$srcTrigger['description'], $dst_trigger['newTriggerExpression'],
-									$depTriggers[$depTrigger['triggerid']]['description'], $expr2
-								));
+				$error = array_key_exists('status', $dst_hosts[$dst_hostid])
+					? _('Trigger "%1$s" cannot depend on the non-existent trigger "%2$s" on the host "%3$s".')
+					: _('Trigger "%1$s" cannot depend on the non-existent trigger "%2$s" on the template "%3$s".');
 
-								return false;
-							}
+				error(sprintf($error, $src_triggers[$src_triggerid]['description'],
+					$src_triggers_up[$src_triggerid_up]['description'], $dst_hosts[$dst_hostid]['host']
+				));
+
+				return false;
+			}
+
+			$dst_host_triggers = CMacrosResolverHelper::resolveTriggerExpressions($dst_host_triggers,
+				['sources' => ['expression', 'recovery_expression']]
+			);
+
+			$dst_host_triggerids = [];
+
+			foreach ($dst_host_triggers as $i => $trigger) {
+				$description = $trigger['description'];
+				$expression = $trigger['expression'];
+				$recovery_expression = $trigger['recovery_expression'];
+
+				if ($src_hostid) {
+					foreach ($trigger['hosts'] as $host) {
+						if (array_key_exists($host['hostid'], $dst_hosts)) {
+							$dst_host_triggerids[$host['hostid']][$description][$expression][$recovery_expression] =
+								$trigger['triggerid'];
 						}
-						else {
-							// Leave original dependency.
+					}
+				}
+				else {
+					$dst_hostid = $trigger['hosts'][0]['hostid'];
 
-							$depTriggerId = $depTrigger['triggerid'];
+					$dst_host_triggerids[$dst_hostid][$description][$expression][$recovery_expression] =
+						$trigger['triggerid'];
+				}
+			}
+
+			foreach ($src_host_dependencies as $src_triggerid_up => $src_triggerids) {
+				foreach ($src_triggerids as $src_triggerid => $foo) {
+					foreach ($trigger_links[$src_triggerid] as $dst_hostid => $i) {
+						$src_trigger_up = $src_triggers_up[$src_triggerid_up];
+						$_src_host = $src_hostid ? $src_host : $src_trigger['hosts'][0]['host'];
+						$dst_host = $dst_hosts[$dst_hostid]['host'];
+
+						$description = $src_trigger_up['description'];
+						$expression =
+							triggerExpressionReplaceHost($src_trigger_up['expression'], $_src_host, $dst_host);
+						$recovery_expression =
+							triggerExpressionReplaceHost($src_trigger_up['recovery_expression'], $_src_host, $dst_host);
+
+						if (array_key_exists($dst_hostid, $dst_host_triggerids)
+								&& array_key_exists($description, $dst_host_triggerids[$dst_hostid])
+								&& array_key_exists($expression, $dst_host_triggerids[$dst_hostid][$description])
+								&& array_key_exists($recovery_expression, $dst_host_triggerids[$dst_hostid][$description][$expression])) {
+							$dst_triggerid_up =
+								$dst_host_triggerids[$dst_hostid][$description][$expression][$recovery_expression];
+
+							$dst_triggers[$i]['dependencies'][] = ['triggerid' => $dst_triggerid_up];
 						}
+						else {
+							$error = array_key_exists('status', $dst_hosts[$dst_hostid])
+								? _('Trigger "%1$s" cannot depend on the non-existent trigger "%2$s" on the host "%3$s".')
+								: _('Trigger "%1$s" cannot depend on the non-existent trigger "%2$s" on the template "%3$s".');
+
+							error(sprintf($error, $description, $src_trigger_up['description'], $dst_host));
 
-						$dependencies[] = [
-							'triggerid' => $dst_trigger['newTriggerId'],
-							'dependsOnTriggerid' => $depTriggerId
-						];
+							return false;
+						}
 					}
 				}
 			}
 		}
+	}
 
-		if ($dependencies) {
-			if (!API::Trigger()->addDependencies($dependencies)) {
-				return false;
-			}
+	if ($dst_triggers) {
+		$result = API::Trigger()->update(array_values($dst_triggers));
+
+		if (!$result) {
+			return false;
 		}
 	}
 
@@ -433,22 +486,6 @@ function triggerExpressionReplaceHost(string $expression, string $src_host, stri
 	return $expression;
 }
 
-function replace_template_dependencies($deps, $hostid) {
-	foreach ($deps as $id => $val) {
-		$sql = 'SELECT t.triggerid'.
-				' FROM triggers t,functions f,items i'.
-				' WHERE t.triggerid=f.triggerid'.
-					' AND f.itemid=i.itemid'.
-					' AND t.templateid='.zbx_dbstr($val).
-					' AND i.hostid='.zbx_dbstr($hostid);
-		if ($db_new_dep = DBfetch(DBselect($sql))) {
-			$deps[$id] = $db_new_dep['triggerid'];
-		}
-	}
-
-	return $deps;
-}
-
 /**
  * Prepare arrays containing only hosts and triggers that will be shown results table.
  *
diff --git a/ui/include/views/configuration.triggers.edit.php b/ui/include/views/configuration.triggers.edit.php
index 83e6255c3b3..fc3efc04ca9 100644
--- a/ui/include/views/configuration.triggers.edit.php
+++ b/ui/include/views/configuration.triggers.edit.php
@@ -600,7 +600,7 @@ $dependenciesFormList = new CFormList('dependenciesFormList');
 $dependenciesTable = (new CTable())
 	->setId('dependency-table')
 	->setAttribute('style', 'width: 100%;')
-	->setHeader([_('Name'), $readonly ? null : _('Action')]);
+	->setHeader([_('Name'), $discovered_trigger ? null : _('Action')]);
 
 foreach ($data['db_dependencies'] as $dependency) {
 	$triggersForm->addVar('dependencies[]', $dependency['triggerid'], 'dependencies_'.$dependency['triggerid']);
@@ -618,7 +618,7 @@ foreach ($data['db_dependencies'] as $dependency) {
 					->setArgument('context', $data['context'])
 			))->setTarget('_blank'),
 			(new CCol(
-				$readonly
+				$discovered_trigger
 					? null
 					: (new CButton('remove', _('Remove')))
 						->onClick('view.removeDependency('.json_encode($dependency['triggerid']).')')
@@ -632,7 +632,7 @@ foreach ($data['db_dependencies'] as $dependency) {
 $dependenciesFormList->addRow(_('Dependencies'),
 	(new CDiv([
 		$dependenciesTable,
-		$readonly
+		$discovered_trigger
 			? null
 			: (new CButton('bnt1', _('Add')))
 				->onClick(
diff --git a/ui/include/views/monitoring.sysmap.edit.php b/ui/include/views/monitoring.sysmap.edit.php
index c0345f7682c..a7731419c56 100644
--- a/ui/include/views/monitoring.sysmap.edit.php
+++ b/ui/include/views/monitoring.sysmap.edit.php
@@ -344,7 +344,7 @@ $user_groups = [];
 
 foreach ($data['sysmap']['userGroups'] as $user_group) {
 	$user_groupid = $user_group['usrgrpid'];
-	$user_groups[$user_groupid] = [
+	$user_groups[] = [
 		'usrgrpid' => $user_groupid,
 		'name' => $data['user_groups'][$user_groupid]['name'],
 		'permission' => $user_group['permission']
@@ -381,14 +381,14 @@ $users = [];
 
 foreach ($data['sysmap']['users'] as $user) {
 	$userid = $user['userid'];
-	$users[$userid] = [
+	$users[] = [
 		'id' => $userid,
 		'name' => getUserFullname($data['users'][$userid]),
 		'permission' => $user['permission']
 	];
 }
 
-$js_insert .= 'window.addPopupValues('.zbx_jsvalue(['object' => 'userid', 'values' => $users]).');';
+$js_insert .= 'window.addPopupValues('.json_encode(['object' => 'userid', 'values' => $users]).');';
 
 zbx_add_post_js($js_insert);
 
diff --git a/ui/templates.php b/ui/templates.php
index 400c9ac5d99..f5623caeb35 100644
--- a/ui/templates.php
+++ b/ui/templates.php
@@ -333,17 +333,8 @@ elseif (hasRequest('add') || hasRequest('update')) {
 			}
 
 			// copy triggers
-			$dbTriggers = API::Trigger()->get([
-				'output' => ['triggerid'],
-				'hostids' => $cloneTemplateId,
-				'inherited' => false
-			]);
-
-			if ($dbTriggers) {
-				if (!copyTriggersToHosts(zbx_objectValues($dbTriggers, 'triggerid'), $input_templateid,
-						$cloneTemplateId)) {
-					throw new Exception();
-				}
+			if (!copyTriggersToHosts([$input_templateid], $cloneTemplateId)) {
+				throw new Exception();
 			}
 
 			// copy graphs
diff --git a/ui/tests/api_json/testTemplate.php b/ui/tests/api_json/testTemplate.php
index 14bec3e5311..8441ad15ca1 100644
--- a/ui/tests/api_json/testTemplate.php
+++ b/ui/tests/api_json/testTemplate.php
@@ -272,7 +272,7 @@ class testTemplate extends CAPITest {
 					['templateid' => $templateids[2]]
 				]
 			]
-		], 'Cannot link template "test-template-double-link-01" to template "test-template-double-link-04" because its parent template "test-template-double-link-01" will be linked twice.');
+		], 'Cannot link template "test-template-double-link-01" to template "test-template-double-link-04", because its parent template "test-template-double-link-01" would be linked twice.');
 	}
 
 	public function testTemplate_CreateTriggerDependency() {
diff --git a/ui/tests/api_json/testTriggerValidation.php b/ui/tests/api_json/testTriggerValidation.php
index cae85a10781..fb59239a390 100644
--- a/ui/tests/api_json/testTriggerValidation.php
+++ b/ui/tests/api_json/testTriggerValidation.php
@@ -107,7 +107,7 @@ class testTriggerValidation extends CAPITest {
 						]
 					]
 				],
-				'expected_error' => 'Cannot create circular dependencies.'
+				'expected_error' => 'Trigger "test-trigger-1" cannot depend on the trigger "test-trigger-2", because a circular linkage ("test-trigger-2" -> "test-trigger-1" -> "test-trigger-2") would occur.'
 			],
 			'delete trigger name' => [
 				'triggers' => [
@@ -129,7 +129,7 @@ class testTriggerValidation extends CAPITest {
 						]
 					]
 				],
-				'expected_error' => 'Cannot create dependency on trigger itself.'
+				'expected_error' => 'Trigger "test-trigger-1" cannot depend on the trigger "test-trigger-1", because a circular linkage ("test-trigger-1" -> "test-trigger-1") would occur.'
 			],
 			'update read-only properties' => [
 				'triggers' => [
@@ -392,7 +392,7 @@ class testTriggerValidation extends CAPITest {
 						]]
 					]
 				],
-				'expected_error' => 'Cannot add dependency from a host to a template.'
+				'expected_error' => 'Trigger "Trigger with invalid dependencies" cannot depend on the trigger "template-trigger", because dependencies of host triggers on template triggers are not allowed.'
 			],
 			'Trigger with invalid dependencies #3' => [
 				'triggers' => [
diff --git a/ui/tests/include/web/CElement.php b/ui/tests/include/web/CElement.php
index 6cd81b83988..1fd95f14912 100644
--- a/ui/tests/include/web/CElement.php
+++ b/ui/tests/include/web/CElement.php
@@ -500,7 +500,8 @@ class CElement extends CBaseElement implements IWaitable {
 	* @inheritdoc
 	*/
 	public function isEnabled($enabled = true) {
-		$classes = explode(' ', parent::getAttribute('class'));
+		$attribute = parent::getAttribute('class');
+		$classes = ($attribute !== null) ? explode(' ', $attribute) : [];
 
 		$is_enabled = parent::isEnabled()
 				&& (parent::getAttribute('disabled') === null)
diff --git a/ui/tests/include/web/CElementCollection.php b/ui/tests/include/web/CElementCollection.php
index 67ab8c9e349..76835c261f2 100644
--- a/ui/tests/include/web/CElementCollection.php
+++ b/ui/tests/include/web/CElementCollection.php
@@ -61,13 +61,14 @@ class CElementCollection implements Iterator {
 	/**
 	 * @inheritdoc
 	 */
-	public function rewind() {
+	public function rewind(): void {
 		reset($this->elements);
 	}
 
 	/**
 	 * @inheritdoc
 	 */
+	#[\ReturnTypeWillChange]
 	public function current() {
 		return current($this->elements);
 	}
@@ -75,6 +76,7 @@ class CElementCollection implements Iterator {
 	/**
 	 * @inheritdoc
 	 */
+	#[\ReturnTypeWillChange]
 	public function key() {
 		return key($this->elements);
 	}
@@ -82,14 +84,14 @@ class CElementCollection implements Iterator {
 	/**
 	 * @inheritdoc
 	 */
-	public function next() {
-		return next($this->elements);
+	public function next(): void {
+		next($this->elements);
 	}
 
 	/**
 	 * @inheritdoc
 	 */
-	public function valid() {
+	public function valid(): bool {
 		$key = $this->key();
 
 		return ($key !== null && $key !== false);
@@ -100,7 +102,7 @@ class CElementCollection implements Iterator {
 	 *
 	 * @return integer
 	 */
-	public function count() {
+	public function count(): int {
 		return count($this->elements);
 	}
 
@@ -109,7 +111,7 @@ class CElementCollection implements Iterator {
 	 *
 	 * @return boolean
 	 */
-	public function isEmpty() {
+	public function isEmpty(): bool {
 		return ($this->elements === []);
 	}
 
@@ -120,7 +122,7 @@ class CElementCollection implements Iterator {
 	 *
 	 * @throws Exception
 	 */
-	public function first() {
+	public function first(): CElement {
 		$element = reset($this->elements);
 
 		if ($element === false) {
@@ -137,7 +139,7 @@ class CElementCollection implements Iterator {
 	 *
 	 * @throws Exception
 	 */
-	public function last() {
+	public function last(): CElement {
 		$element = end($this->elements);
 
 		if ($element === false) {
@@ -154,7 +156,7 @@ class CElementCollection implements Iterator {
 	 *
 	 * @return boolean
 	 */
-	public function exists($key) {
+	public function exists($key): bool {
 		return array_key_exists($key, $this->elements);
 	}
 
@@ -163,9 +165,9 @@ class CElementCollection implements Iterator {
 	 *
 	 * @param mixed $key    array key
 	 *
-	 * @return boolean
+	 * @return CElement
 	 */
-	public function get($key) {
+	public function get($key): CElement {
 		return $this->elements[$key];
 	}
 
@@ -175,7 +177,7 @@ class CElementCollection implements Iterator {
 	 * @param mixed $key        array key
 	 * @param mixed $element    element to be set
 	 */
-	public function set($key, $element) {
+	public function set($key, $element): void {
 		$this->elements[$key] = $element;
 	}
 
diff --git a/ui/tests/include/web/elements/CTableElement.php b/ui/tests/include/web/elements/CTableElement.php
index 44d4bc764e5..41215230a25 100644
--- a/ui/tests/include/web/elements/CTableElement.php
+++ b/ui/tests/include/web/elements/CTableElement.php
@@ -186,7 +186,7 @@ class CTableElement extends CElement {
 	public function findRows($param, $data = []) {
 		$rows = [];
 
-		if (is_callable($param)) {
+		if ($param instanceof \Closure) {
 			foreach ($this->getRows() as $i => $row) {
 				if (call_user_func($param, $row)) {
 					$rows[$i] = $row;
diff --git a/ui/tests/selenium/testTriggerDependencies.php b/ui/tests/selenium/testTriggerDependencies.php
index fe4c9aa408a..1e4404740ba 100644
--- a/ui/tests/selenium/testTriggerDependencies.php
+++ b/ui/tests/selenium/testTriggerDependencies.php
@@ -20,6 +20,7 @@
 
 require_once dirname(__FILE__).'/../include/CLegacyWebTest.php';
 require_once dirname(__FILE__).'/../include/helpers/CDataHelper.php';
+require_once dirname(__FILE__).'/behaviors/CMessageBehavior.php';
 
 use Facebook\WebDriver\WebDriverBy;
 
@@ -29,6 +30,14 @@ use Facebook\WebDriver\WebDriverBy;
  * @onBefore prepareTemplateData
  */
 class testTriggerDependencies extends CLegacyWebTest {
+
+	/**
+	 * Attach MessageBehavior to the test.
+	 */
+	public function getBehaviors() {
+		return [CMessageBehavior::class];
+	}
+
 	const TEMPLATE_AGENT = 'Zabbix agent';
 	const TEMPLATE_FREEBSD = 'FreeBSD by Zabbix agent';
 	const TEMPLATE_APACHE = 'Apache by HTTP';
@@ -64,58 +73,80 @@ class testTriggerDependencies extends CLegacyWebTest {
 	/**
 	 * @dataProvider getTriggerDependenciesData
 	 */
-	public function testTriggerDependenciesFromHost_SimpleTest($trigger, $template, $dependencies, $expected) {
+	public function testTriggerDependenciesFromHost_SimpleTest($data) {
 		// Get the id of template to be updated based on the template that owns the trigger in dependencies tab.
 		$ids = [
 			self::TEMPLATE_AGENT => self::$agent_templateid,
 			self::TEMPLATE_APACHE => self::$apache_templateid
 		];
-		$update_id = ($template === self::TEMPLATE_APACHE) ? $ids[self::TEMPLATE_APACHE] : $ids[self::TEMPLATE_AGENT];
+		$update_id = ($data['template'] === self::TEMPLATE_APACHE) ? $ids[self::TEMPLATE_APACHE] : $ids[self::TEMPLATE_AGENT];
 
 		$this->zbxTestLogin('triggers.php?filter_set=1&context=template&filter_hostids[0]='.$update_id);
 		$this->zbxTestCheckTitle('Configuration of triggers');
 
-		$this->zbxTestClickLinkTextWait($trigger);
+		$this->zbxTestClickLinkTextWait($data['trigger']);
 		$this->zbxTestClickWait('tab_dependenciesTab');
 
 		$this->zbxTestClick('bnt1');
 		$this->zbxTestLaunchOverlayDialog('Triggers');
 		$host = COverlayDialogElement::find()->one()->query('class:multiselect-control')->asMultiselect()->one();
 		$host->fill([
-			'values' => $template,
+			'values' => $data['template'],
 			'context' => 'Templates'
 		]);
-		$this->zbxTestClickLinkTextWait($dependencies);
+		$this->zbxTestClickLinkTextWait($data['dependency']);
 		$this->zbxTestWaitUntilElementVisible(WebDriverBy::id('bnt1'));
 		$this->zbxTestClickWait('update');
-		$this->zbxTestTextPresent($expected);
+		if ($data['expected'] === TEST_BAD) {
+			$this->assertMessage(TEST_BAD, 'Cannot update trigger', $data['error_message']);
+		}
+		else {
+			$this->assertMessage(TEST_GOOD, 'Trigger updated');
+		}
 	}
 
 	public function getTriggerDependenciesData() {
 		return [
 			[
-				'Zabbix agent is not available',
-				self::TEMPLATE_FREEBSD,
-				'/etc/passwd has been changed on FreeBSD by Zabbix agent',
-				'Not all templates are linked to'
+				[
+					'expected' => TEST_BAD,
+					'trigger' => 'Zabbix agent is not available',
+					'template' => self::TEMPLATE_FREEBSD,
+					'dependency' => '/etc/passwd has been changed on FreeBSD by Zabbix agent',
+					'error_message' => 'Trigger "Zabbix agent is not available" cannot depend on the trigger "/etc/passwd has been changed'.
+							' on {HOST.NAME}" from the template "FreeBSD by Zabbix agent", because dependencies on triggers'.
+							' from a child template or host are not allowed.'
+				]
 			],
 			[
-				'Apache: Service is down',
-				self::TEMPLATE_APACHE,
-				'Apache: Service response time is too high',
-				'Cannot create circular dependencies.'
+				[
+					'expected' => TEST_BAD,
+					'trigger' => 'Apache: Service is down',
+					'template' => self::TEMPLATE_APACHE,
+					'dependency' => 'Apache: Service response time is too high',
+					'error_message' => 'Trigger "Apache: Service is down" cannot depend on the trigger "Apache: Service response'.
+							' time is too high", because a circular linkage ("Apache: Service response time is too high" ->'.
+							' "Apache: Service is down" -> "Apache: Service response time is too high") would occur.'
+				]
 			],
 			[
-				'Apache: has been restarted',
-				self::TEMPLATE_APACHE,
-				'Apache: has been restarted',
-				'Cannot create dependency on trigger itself.'
+				[
+					'expected' => TEST_BAD,
+					'trigger' => 'Apache: has been restarted',
+					'template' => self::TEMPLATE_APACHE,
+					'dependency' => 'Apache: has been restarted',
+					'error_message' => 'Trigger "Apache: has been restarted" cannot depend on the trigger "Apache: '.
+							'has been restarted", because a circular linkage ("Apache: has been restarted" -> "Apache: '.
+							'has been restarted") would occur.'
+				]
 			],
 			[
-				'Apache: has been restarted',
-				self::TEMPLATE_APACHE,
-				'Apache: Service is down',
-				'Trigger updated'
+				[
+					'expected' => TEST_GOOD,
+					'trigger' => 'Apache: has been restarted',
+					'template' => self::TEMPLATE_APACHE,
+					'dependency' => 'Apache: Service is down'
+				]
 			]
 		];
 	}
diff --git a/ui/triggers.php b/ui/triggers.php
index f79c209ca10..62ec7d9506b 100644
--- a/ui/triggers.php
+++ b/ui/triggers.php
@@ -523,7 +523,7 @@ elseif (hasRequest('action') && getRequest('action') === 'trigger.masscopyto' &&
 
 		DBstart();
 
-		$result = copyTriggersToHosts(getRequest('g_triggerid'), $hosts_ids, getRequest('hostid'));
+		$result = copyTriggersToHosts($hosts_ids, getRequest('hostid'), getRequest('g_triggerid'));
 		$result = DBend($result);
 
 		$triggers_count = count(getRequest('g_triggerid'));