On delete on relation leads to System.UnreferencedFile create failed for security reasons

I do have a entity, lets call it Center and a few surrounding entites. These surrounding entities do have relations to the Center entity. Some 1:1 some *:1 and some *:1. All of them do have the “On delete of Center → Delete the surrounding entities too” defined on the relation.  Now when i try to delete a Center entity I get the following error: Creating object of type System.UnreferencedFile by user Admin_xyz failed for security reasons: User 'Admin_xyz' attempted to create an object of type 'System.UnreferencedFile', but does not have the required permissions I could not find a UnreferencedFile entity in the Systems package. What is going on here? When i remove all of the “On delete → Delete surrounding”s the error disappears. But as soon as i add one of them, it reappears. I could not reproduce this on a freshly created app (directly with 9.1.0). Background: Mendix 9.1.0 App was migrated from 9.0.5, 8.18 and originally created with 8.16
1 answers

Could it be that you do not have access to change the all the references but have only read rights instead of read write rights? I would double check those to make sure you are allowed to change it to empty.