This has already been answered but just in case someone comes here from a search engine looking for info on the We have a space info key for a block group that doesn't exist message (unrelated to OP's issue) - don't worry. I think something has changed recently in btrfs because I got it on a fresh Ubuntu install on an NVMe and have noticed it multiple times on multiple drives, HDD or not, when trying to resize them with gparted. You can run a scrub if you are worried. Running either btrfs-rescue clear-space-cache (v1|v2) /dev/xxx or btrfs-check --clear-space-cache (v1|v2) /dev/xxx. It seems Sorry for the somewhat unrelated reply, this was one of the first threads that came up when I was looking into the issue.