I had a spectaculr Ubuntu LTS upgrade failure on a server earlier this year because I had inadvertently left a terminal open running a command with 'su'. It tr

I had a spectaculr Ubuntu LTS upgrade failure on a server earlier this year because I had inadvertently left a terminal open running a command with 'su'. It transpires that the sudo binary cannot be upgraded when su is active, so the entire upgrade cascade-failed and left me with a broken and unbootable system. Had to start from bare-metal.