Has anyone attempted to backup from an old version such as 6.2 and restore into 6.4? We are struggling to debug a simple upgrade from 6.2 to 6.3 trying to get to 6.4 but getting stuck. Maybe it is possible to jump using the backup and restore route?
I never tried that for 6.2->6.4 - but other version jumps worked. Have you tried a db:migrate after the restore?
If the upgrade already fails, most likely something with your database is not in order. You’ll have to fix that, but without any further information from your end (e.g. error messages…) nobody will be able to help you. At all.