4 files changed, 24 insertions, 4 deletions

diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index e0f89024420..db93193bfe3 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -27,7 +27,7 @@
  * \note Use #STRINGIFY() rather than defining with quotes.
  */
 #define BLENDER_VERSION 281
-#define BLENDER_SUBVERSION 4
+#define BLENDER_SUBVERSION 5
 /** Several breakages with 280, e.g. collections vs layers. */
 #define BLENDER_MINVERSION 280
 #define BLENDER_MINSUBVERSION 0
diff --git a/source/blender/blenkernel/intern/collection.c b/source/blender/blenkernel/intern/collection.c
index 2031576190e..06710b40569 100644
--- a/source/blender/blenkernel/intern/collection.c
+++ b/source/blender/blenkernel/intern/collection.c
@@ -338,8 +338,9 @@ Collection *BKE_collection_duplicate(Main *bmain,
                                      const bool do_obdata)
 {
   /* It's not allowed to copy the master collection. */
+  BLI_assert((collection->id.flag & LIB_PRIVATE_DATA) == 0);
+  BLI_assert((collection->flag & COLLECTION_IS_MASTER) == 0);
   if (collection->flag & COLLECTION_IS_MASTER) {
-    BLI_assert("!Master collection can't be duplicated");
     return NULL;
   }
 
@@ -368,6 +369,7 @@ Collection *BKE_collection_duplicate(Main *bmain,
 Collection *BKE_collection_copy_master(Main *bmain, Collection *collection, const int flag)
 {
   BLI_assert(collection->flag & COLLECTION_IS_MASTER);
+  BLI_assert(collection->id.flag & LIB_PRIVATE_DATA);
 
   Collection *collection_dst = MEM_dupallocN(collection);
   BKE_collection_copy_data(bmain, collection_dst, collection, flag);
@@ -499,6 +501,7 @@ Collection *BKE_collection_master_add()
   /* Not an actual datablock, but owned by scene. */
   Collection *master_collection = MEM_callocN(sizeof(Collection), "Master Collection");
   STRNCPY(master_collection->id.name, "GRMaster Collection");
+  master_collection->id.flag |= LIB_PRIVATE_DATA;
   master_collection->flag |= COLLECTION_IS_MASTER;
   return master_collection;
 }
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index ed3b1613b2a..00c0ed561f7 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -3704,12 +3704,23 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     FOREACH_MAIN_ID_END;
   }
 
-  {
-    /* Versioning code until next subversion bump goes here. */
+  if (!MAIN_VERSION_ATLEAST(bmain, 281, 5)) {
     for (Brush *br = bmain->brushes.first; br; br = br->id.next) {
       if (br->ob_mode & OB_MODE_SCULPT && br->normal_radius_factor == 0.0f) {
         br->normal_radius_factor = 0.5f;
       }
     }
+
+    LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+      /* Older files do not hqve a msater collection, which is then added through
+       * `BKE_collection_master_add()`, so everything is fine. */
+      if (scene->master_collection != NULL) {
+        scene->master_collection->id.flag |= LIB_PRIVATE_DATA;
+      }
+    }
+  }
+
+  {
+    /* Versioning code until next subversion bump goes here. */
   }
 }
diff --git a/source/blender/makesrna/intern/rna_access.c b/source/blender/makesrna/intern/rna_access.c
index bc015a378cc..531c2ef2003 100644
--- a/source/blender/makesrna/intern/rna_access.c
+++ b/source/blender/makesrna/intern/rna_access.c
@@ -41,6 +41,7 @@
 #include "BLT_translation.h"
 
 #include "BKE_animsys.h"
+#include "BKE_collection.h"
 #include "BKE_context.h"
 #include "BKE_idcode.h"
 #include "BKE_idprop.h"
@@ -5778,6 +5779,11 @@ ID *RNA_find_real_ID_and_path(Main *bmain, ID *id, const char **r_path)
           *r_path = "node_tree";
         }
         return BKE_node_tree_find_owner_ID(bmain, (bNodeTree *)id);
+      case ID_GR:
+        if (r_path) {
+          *r_path = "collection";
+        }
+        return (ID *)BKE_collection_master_scene_search(bmain, (Collection *)id);
 
       default:
         return NULL;