Some ppl are missing the point. Ignore any instructions that are telling you to repeat any upgrades - you clearly have a btrfs (filesystem) corruption that needs to be sorted out. I don’t use btrfs in a while but if you’re lucky then a ‘btrfs-check’ should be able to fix it. You need to boot from an install/live disk, and run the command on your disk, without installing, nor mounting the disk.

Boot a live environment, chroot in to it and re-run the update.