It is possible - but officially discouraged - to do a dist-upgrade on Ubuntu. Sometimes it works, other times it 'almost' works. It is the latter problem which

It is possible - but officially discouraged - to do a dist-upgrade on Ubuntu. Sometimes it works, other times it 'almost' works. It is the latter problem which makes the official discouragement a reasonable precaution against breakage. Things like the mysql->mariadb migration in Debian might necessitate manual intervention but this is made clear from the onset.