Unless support can help you are probably going to need to delete the offending destination volumes and start over.
sounds like you did a “major” upgrade (like 9.11.1 to 9.12.1, changing that middle number) where it is possible for features to change.
you might get lucky if you upgrade the other side of the mirror if you can.
bottom line, read the upgrade guide. I’m pretty sure it tells you to quiesce snapmirror operations before upgrading and I’m also pretty sure during validation you got a warning about snapmirror.