Weird issue where Cinnamon won’t start properly after doing an update and reboot of Linux Mint 21.3
After I started up my computer, having updated the last time I used it, going past the log in screen just shows the lock-screen background for a little bit, before a black screen with just a cursor. The Lock Screen still works if I shut the laptop lid or leave the computer enough, but the screen doesn’t seem to turn off properly when shutting the lid and most keyboard shortcuts don’t work, though I can still go to tty.
I tried updating. I tried reinstalling Cinnamon. That didn’t work, but installing lxde and selecting that at login worked, but Cinnamon still doesn’t.
I eventually found out that right clicking the black screen Cinnamon desktop still works, and I can get windows such as the terminal like that, but the windows won’t move or resize.
Go to a TTY by pressing Ctrl + Alt + F3. Replace F3 with F4, F5, F6 etc if you are already on that TTY. Once you are in TTY, login with your user and its password. Then run cinnamon --replace. If it runs without any problems, the problem might be related to your display manager. If it doesn't start, you should see the errors.
This seems to be an error that traced back to Mutter, since Muffin (CInnamon's window manager) is a fork of it I believe they are related. Maybe an upgrade solve this? The post says you are on 21.3, so while on TTY, do an upgrade to see if that works.
Purge is used when you want something to be deleted completely, and autoremove is used to clean the rest of the unused dependencies. If those didn't fix the issue, this could be about your user or user's home directory. Though the errors indicate a session problem.
You can try to reset all Cinnamon configuration. dconf reset -f /org/cinnamon/
That will delete everything you changed on Cinnamon so you may want to backup your settings.
Oh my, so sorry about this. Sometimes I tend to not to write a word I'm thinking when I write and it happened to be a command. -_-
It should be sudo useradd newuser and you also need to attend a password to it so it can login sudo passwd newuser.
Since you can login with LXDE I don't think it's graphics driver related. Maybe changing a display manager would work but I'm not so warm about it. This looks like something low-level went wrong.