This might warrant its own issue, but I found that my database for my several-year-old server had some inconsistent rows in the ACL table. Specifically, there were ACLs referencing groups which no longer existed.

The migration just stops and the server refuses to start (with a helpful error message, nice). I think it's good to err on the side of caution, but in this case I think it might be okay to just drop the inconsistent ACLs since they wouldn't do anything anyways as the group they reference doesn't exist.

Originally posted by @dexgs in #6935