Fixes #7368 - Do not set user id when it's set to empty string or it would set the same visitor id to all those visitors

1 files changed, 3 insertions, 0 deletions

diff --git a/js/piwik.js b/js/piwik.js
index 27413028ff..0f4f5d253a 100644
--- a/js/piwik.js
+++ b/js/piwik.js
@@ -4245,6 +4245,9 @@ if (typeof Piwik !== 'object') {
                  * @param string User ID
                  */
                 setUserId: function (userId) {
+                    if(!isDefined(userId) || !userId.length) {
+                        return;
+                    }
                     configUserId = userId;
                     visitorUUID = hash(configUserId).substr(0, 16);
                 },