When migrating/restoring MM on a new server, all public chats are there, however private chats and groups are apparently missing, names are missing from public chats (all messages show up as somebody).
Steps to reproduce
Ensure both servers have the same version of MM. Currently using MM version 5.12.4 bundled with GitLab Omnibus version 12.1.6
Restored GitLab data successfully and ensured that MM was working (although empty)
Made a backup of MM DB and data files and shipped them off to new server
Ran gitlab-ctl reconfigure to generate config.json. Since gitlab.rb was the same as on the old server (with changes pertaining to gitlab alone), the config.json file generated should be the same as on the old server and therefore I didn’t restore that.
Restored DB and datafiles
Expected behavior
Accessing MM should show me all my previous DMs, Private channels, customisations (colour scheme etc.)
Observed behavior
All DMs are missing. When starting a DM with a user again, all history is absent
Private channels are missing. Recreating a channel and it appears empty
All customisations are missing. Favourites, notification settings, colour schemes etc.
Minor Updates
I’m not sure if this is relevant or not, but since I’m still testing the process, I’m doing so with an alternative domain name. So, old GitLab/MM server is still working fine on gitlab.example.com and mattermost.example.com and the migrated services are all on gitlab-test…* and mattermost-test…*. I have however changed the relevant settings (external URLs, oauth callback urls etc.)