scripts-blender/addons/asset_pipeline_2/merge/core.py

@@ -179,15 +179,14 @@ def merge_task_layer(
     external_col = bpy.data.collections[f"{col_base_name}.{external_suffix}"]
 
     map = AssetTransferMapping(local_col, external_col, local_tls)
-
-    if len(map.conflict_transfer_data) != 0:
     error_msg = ''
+    if len(map.conflict_transfer_data) != 0:
         for conflict in map.conflict_transfer_data:
             error_msg += f"Transfer Data conflict found for '{conflict.name}' on obj '{conflict.id_data.name}'\n"
         return error_msg
 
     if len(map.conflict_ids) != 0:
-        error_msg = ''
+        
         for conflict_obj in map.conflict_ids:
             type_name = get_id_type_name(type(conflict_obj))
             error_msg += (
@@ -197,12 +196,22 @@ def merge_task_layer(
 
     # Remove all transfer data from target objects
     for source_obj in map.object_map:
+        if source_obj.data.users > 1:
+            error_msg += (
+                f"Object {source_obj.name} contains multi-user datablock'\n"
+            )
+            return error_msg
         target_obj = map.object_map[source_obj]
         target_obj.transfer_data_ownership.clear()
 
     apply_transfer_data(context, map.transfer_data_map)
 
     for source_obj in map.object_map:
+        if target_obj.data.users > 1:
+            error_msg += (
+                f"Object {source_obj.name} contains multi-user datablock'\n"
+            )
+            return error_msg
         target_obj = map.object_map[source_obj]
         remap_user(source_obj, target_obj)
         transfer_data_clean(target_obj)