Probably someone will throw a better answer for DB migration, but the problem is not DB migration here, TBH db part seems to me the easiest part but what they d

Probably someone will throw a better answer for DB migration, but the problem is not DB migration here, TBH db part seems to me the easiest part but what they did is migrating entire stack not by part by part, without pilots and using poor testing. Migrating whole stack at one click is nuclear I believe poor planning had a great role to force them to get it done.