Ubuntu boots to black screen with cursor after upgrade (from 18.04 to 20.04)

Ok, so I would try to re-install the GUI / Desktop:

sudo apt update
sudo apt upgrade
sudo apt autoremove

sudo apt remove ubuntu-desktop
sudo apt autoremove
sudo apt install ubuntu-desktop

or

sudo apt-get install ubuntu-gnome-desktop

or. one could try sudo apt-get install --reinstall ubuntu-gnome-desktop

or whatever desktop you have (can be xfce4, kde, or something else although I have not tried all of the options, but xfce4 seems to work flawless.)

Edit: related Reinstall Gnome

Just in case this wouldn't work for someone in the future:

• You can always try to install another (different) GUI/Desktop: Like LXDE, and from there (when you have a working GUI/Desktop) Maybe try different things?

Extremely glad it worked and that I could help!

Note: I have noticed that

• *This seems to be a very, very common problem (Because I have often, and some of my friends - had this problem, some other problem that (in my case) was after this worked; was the Ubuntu was laggy, but in my case it resolved itself to just, install drivers & update the OS and reboot.

  (In case this would be the issue after, this could be a good thing to try)*

Edit: If some has problems with installing drivers

(e.g Nvidia) I would highly suggest checking out Smaili's Great answer here - (Since it's the same version, too - and driver problems can often come after a solution like this above)

Thanks!

regards.