When a database that is ran as a service is upgraded, the database should be unregistered first in the new version and then re-registered as a service


So if the database that was originally in 4D v15 is upgraded to 4D v16, the database should be opened (as admin) on 4D v16 Server. The menu item under File->Unregister Current Database should be selected first. Then the menu item File->Register Current Database should be re-selected.