Kubuntu shows black screen after upgrading to 16.04

Question

I upgraded my Kubuntu 15.10 machine to 16.04 yesterday. Everything was working fine. Today, I did a reboot. Upon logging in, my desktop doesn't show so I have a blank black screen. Thankfully, Plank was able to start so I have access to a terminal, file browser, and Chrome.

What can I do to fix this? I'm assuming this is a problem with Plasma, but I honestly don't know.

Solution 1

The problem was that kscreen got uninstalled somehow. I reinstalled it and the problem was fixed.

Solution 2

I was stuck with a splash screen going straight to a black screen, with no graphical login.

To fix this, I purged nvidia-*, installed nouveau, and then realized that both lightdm and sddm were installed. I purged both of those and reinstalled sddm.

Solution 3

I had a black screen also on an old Thinkpad T43p after upgrade form 14.04 -> 16.04. It was fixed after

sudo apt-get install --reinstall sddm; sudo dpkg-reconfigure sddm

After reboot I my had graphical login, but my user was missing (UID=501).

Fixing required creation of /etc/sddm.conf with lines

[Users]
MinimumUid=500

Comments

[0x450]

Actually I was having the same problem and managed to solve it after a rough battle with my nVidia drivers. May I ask whether you have a nVidia graphic card?

[b1uepear]

@0x450 I don't have an Nvidia card.

[Daniels Šatcs]

This worked, thank you. Nvidia driver turned out to be the cause.