I performed Gitlab Instance migration to a new VM and followed a method which was NOT using the typical backup+restore method but rather I reattached the Block Volume to the New VM and ran a Gitlab Reconfigure.
Everything seemed to work well but the Runners in the Admin Panel were unresponsive unlike the backup+restore method where they were available just after the restore. The Runners here only started working properly after I ran a gitlab-runner restart in my Runner VM.
Did you restore /etc/gitlab/gitlab.rb and /etc/gitlab/gitlab-secrets.json? If you missed the secrets file, that would explain why it doesn’t work. Storage under /var/opt/gitlab is only one part of a Gitlab installation.
I have few questions which might help me in my migration, can you please take a look at them?
When you attached Block volume to the new VM, did you have to do any changes in root volume structure? Like creating LVM etc so that new instance has exactly same directory structure as the old one?
After Backup+restore, my runners from previous instance are not showing up in new instance. Were you able to get your runners on new instance after backup and restore? (I retained original gitlab.rb and secrets.json file but still runners are not showing up )