After taking a closer look I think it is a bug for which I proposed a fix and not data corruption of the content of the Action table. To confirm this it would be helpful to get a copy of the original database for forensic purposes to figure out exactly in which case the Action.RepoID referenced a Repository.ID that did not exist and for which user it happened. Although I was able to reproduce the problem for users with admin rights, it looks like there is another use case that leads to the same problem even if the user has no admin rights.