Backup neglects empty folders, restoration results in problems
After migrating gitlab between servers via backup/restore we've found that some users are unable to fork repos.
What appears to be the cause is that the users encountering the issue do not have a folder in /var/opt/gitlab/git-data/repositories/
. Having the user create a dummy repo in their account creates the necessary folder[s] and they can then fork other repos.
New users created since the migration do not have this issue, as gitlab appears to create the necessary folder structure.
edit: Looking through the structure of the backup archive it doesn't seem like much more than the repos themselves are in here. I suppose the flaw is that the fork process isn't creating the necessary folder structure if it doesn't already exist.