Just got round to trying that. This is weird. When I try to login as the new user; this happens:

It just goes to a TTY screen that says [FAILED] Failed to start casper-md5check Verify Live ISO checksums. and then returns to the login screen.

Edit: That same message was shown when I pressed Shud Down, though it did successfully shut down.

Didn’t work. The add command wasn’t found.

Wondering if it might be something to do with my graphics drivers?

E: Unable to locate package cinnamon-settings

Did the reinstall with the rest of them after running purge.

Rebooted and got the same result when trying to run Cinnamon.

You already tried reinstalling CInnamon but can you try it by purging this time, if you already didn’t do it like that?

My command last time was sudo apt install --reinstall cinnamon, so this was my first time “purging”.

Didn’t work.

Is prints “Window manager warning: Unsupported session type”.

How would I do that such that I can see an output?

That’s what I’ve installed on that computer now.

I do still have the 21.3 install though.

I just realised that this is basically the plot of Redo Of Healer.

Points at army: “Fix this!”
Army regresses into infant-hood and is rendered incapable of battle.

Points at own army: “Fix this!”
Army is buffed.

There always the aspect of keeping old hardware alive and useful.