Apparently, "/tmp/update-manager-xxx/apt-btrfs_snapshot.py" does not check the existence of the "btrfs" tool and tries to call it unconditionally. After doing a "apt-get install btrfs-utils" - I don't have any btrfs partition - the upgrade continues.
Apparently, "/tmp/update- manager- xxx/apt- btrfs_snapshot. py" does not check the existence of the "btrfs" tool and tries to call it unconditionally. After doing a "apt-get install btrfs-utils" - I don't have any btrfs partition - the upgrade continues.