This was working yesterday. When I Run the UI list Generic template I get an error: y\utils\__init__.py , line 934, in register register_class(cls) RuntimeError: register_class(...): can t run in readonly state MyPropGroup Not sure why this is, I reset blender to factory that didn't work. Uninstalled blender and deleted user/appdata files for 4.2 and reinstalled. That didn't work either...š This works just fine in 4.3 and used to work in 4.2 not sure what the deal is.