I was playing with xfce and kde with ubuntu 20.04. When I came back to gnome (ubuntu-desktop, same if I use gnome classic), the actual desktop has no icons (I cannot click on it) and there are 'green pixels' randomly in the background (i.e. if I log in/out the green pixels change position in the screen.
I already tried:
-gnome-tweaks: enable icons in desktop (under 'extensions'). It does not work and after I exit gnome-tweaks the button is off again anyway (it does not stay 'on')
-reinstall: gnome, xorg
-reinstall desktop-icons Repeating error: Can't install desktop-icons@csoriano