Ubuntu – Kubuntu 18.04 no more GUI after upgrade from 17.10


I upgraded Kubuntu from 17.10 to 18.04 LTS today. Upgrade went well, until the system rebooted. I got the Kubuntu splash screen, but then: nothing. Black screen. I can however enter TTY 2-6 (1,7,8 not responding). I'm using a laptop with both Intel integrated graphics and NVidia GeForce GT 520 MX graphics card.

I tried:

  • apt update && apt dist-upgrade
  • reconfigure sddm (dpkg-reconfigure sddm)
  • installing different NVidia drivers, as I had problems with the driver last time I installed ubuntu. (nvidia-304- not able to install,nvidia-driver-390, didn't help. nvidia-340: and nouveau, also didn't help
  • Adding 'nomodeset' to /etc/default/grub: no help
  • startx to start the Xserver myself. This results in an error, being that Xserver is not able to start. kstart plasma-desktop shows the following error

    cannot connect to X server

What would be the right way to do it?

Best Answer

After a few hours of trying, I got the GUI working again, thanks to these two posts:

So, this turned out to be a NVidia-driver issue. I reinstalled the NVidia 390 driver, and added the lines suggested in the posts above to the /usr/share/sddm/scripts/Xsetup-file, and in the /etc/X11/xorg.conf-file, a line (Driver "nvidia") in Section "Device" was commented-out, which I enabled again. Rebooted succesfully into the GUI.