For all those people who have been installing stable ROMs, stay away from this latest 'stable' 12.1 release. It should never have been released in the stable channel. Stick to 12.08 for now. And please ignore all those 'beta kings' who seem to have a sarcastic answer for valid concerns.
Most of us don't want the hassle of testing betas, that's exactly why we stick to stable. Never been an issue posting unstable ROMs in this channel so far. Hopefully won't happen again.
Unfortunately, if you've upgraded to 12.1 and need to backup data, I suggest booting into ROM, copy all essential files onto PC, then do a clean install from TWRP by formatting data and using ADB push commands to push 12.08 ROM to phone memory, and installing that.
Don't forget to do a Google backup and backup your accounts as far as possible so when you do a fresh install, it won't be too painful reinstalling all the previous apps.
Good luck. Ignore the uninformed haters.