@jimcarroll don’t forget to backup both old and new encryption keys! They are used for field level encryption, so if you lose them some data will be lost as well. And if you are planing major version upgrade for Postgres I highly recommend to make a dump before you upgrade.
Mine went sideways,
I suppose because I messed up by running upgrade inside alpine based container, while pg itself is running on Ubuntu based container. musl vs libc broke locale metadata and I had to resort to restoring from the dump