16.04: Graphical login/desktop vanished?

[Ralf Mardorf]

On Sun, 24 Jul 2016 23:56:56 +0200, Ralf Mardorf wrote:
>  cd /var/log/
>  grep EE Xorg.0.log
>  sudo tail -60 lightdm/lightdm.log

resp.

   sudo tail -60 lightdm/lightdm.log | less