Boot stuck - how to start GUI from the command line?

During boot, my system is stuck for some reason. I can get to the command line by clicking Ctrl+Alt+F3. After login, what can I do to start the official GUI of Ubuntu 20.04? I tried the following:

 gnome-session gdm3 systemctl isolate graphical 

but none of these worked.

I also tried:

lightdm

and I did see a graphical login screen, but not the usual one; and I could not log in from that screen (I got "authentication error").

I am looking for the most standard and officially-supported solution - I don't need any fancy GUI managers - I just want to get back to work...

2 Answers

lightdm is not the standard Gnome window manager, it is gdm3, so there is some misconfiguration. Easiest way to try to remedy it is to, when logged in, run:

sudo apt-get install --reinstall ubuntu-desktop

and reboot.

On one of my machines (gpu radeon rx560 =)) After the update, the standard shell ubuntu-desktop also did not start. I tried reinstalling the package, reinstalling the drivers. Nothing helped me.

As a result, the problem was solved by installing another package =)

sudo apt-get install xubuntu-desktop

The shell is similar to the standard one. I haven't lost anything. And the main thing is that it worked and did not have to reinstall the system. If your problem is similar to mine. I recommend trying another shell and not bothering.