Workshop

Hi Markus

on contrary to previous posts above, your problem has nothing to do with the Workshop module. Your Moodle database is corrupted though. There are multiple records for the system context found, whereas only a single record is expected. I can't explain how this could happen to you, or how to fix it.

If you don't have many courses, a good alternative might be to install a fresh new Moodle and backup/restore every course to it.