Is the database corrupted? why is that only a specific group data missing?

I have been scratching my head around trying to find either the solution or the root cause. I migrated a server, GLCE form 14 to 16.6.0. Following the upgrade path document 14–> 15–>16. when I was on 15. I add all the data. as soon as I moved to 16, everything was where except the repositories from one group. this groups is basically just all github import used with the command gitlab-rake import.
I cannot find any solution on how to fix this. All the metadata are present except the actual git repo data. when I click on any of the repo it says repo is not available. When I try to delete it I get error 500 not other info in the log why I get error 500.
when I import the repo, it fails. using the api i get name already taken, when I try to delete I get error 500.
what’s causing this? what is the Postgres command to drop everything in this group and the group itself so I can redo the import?