Black screen after login Kubuntu 15.04

I have updated my kubuntu 14.10 to kubuntu 15.04. And now after boot, when I enter my password on welcome screen, I will get black screen. It's looks like screen powered off. No cursor, no change brightness. Nothing. And when I try switch to text consoles (Ctrl+Alt+F1) nothing happening. If I doesn't login in welcome screen I can switch to text console.

Solution 1:

I ended up having to rename ~/.kde, ~/.cache ~/.local and ~/.config.

mv ~/.kde ~/.kde.old
mv ~/.cache ~/.cache.old
mv ~/.local ~/.local.old
mv ~/.config ~/.config.old
shutdown -r now

Not sure exactly which one did the trick but I suspect it was .config.

Solution 2:

This has troubled me for some time now. I noticed it happens when I put Kubuntu to sleep or shut it down with a dual monitor set-up and then trying to start it with the laptop screen only. Anyway, here's what I found - one particular folder is responsible for this mess. Deleting it fixes my problem.

Here's what to do. Once you get the black screen go to a tty (Ctrl+Alt+F1) and do the following:

 rm ~/.local/share/kscreen
 sudo killall sddm

Then enter your password and login. Everything should be ok. Hope this helps ;)

Solution 3:

I may have a solution, I've been trying to figure out what happened for a few days now. Deleting all ~/.cache and ~/.config is not a great idea, as those could be needed but. . .

In ~/.cache, I have deleted only the files with a 14.04 boot DVD, but I have kept the folders:

activityswitcher_wallpaper_preview.kcache
event-sound-cache.tdb.093cbe7e51f0423cb8a1384115f450a1.x86_64-pc-linux-gnu
icon-cache.kcache
ksycoca5
ksycoca5stamp
motd.legal-displayed (0 kb)
plasma-svgelements-air_v1.0
plasma-svgelements-breeze-dark_v0.9.7
plasma_theme_breeze-dark_v0.9.7.kcache
[...]
plasma_wallpaper_preview.kcache

After rebooting, the desktop was fine.

Solution 4:

I too had the same problem in the fresh install of kubuntu 15.04 64 bit.

1. Press Ctrl+Alt+F1 after the system has started
2. System will prompt to login give your login name and press enter

3. Enter the password

   mv ~/.kde ~/.kde.old
   mv ~/.cache ~/.cache.old
   shutdown -r now
   

4. If you can get your gui on next boot don't forget to change 'start with empty session' in 'desktop session' in 'System Settings'

Solution 5:

I had the same issue; the problem was I had two different versions of the nvidia drivers installed. Looks like the dist-upgrade automatically installed nvidia-340, so just run the command below then restart and you should be good.

sudo apt-get purge nvidia-340*