Only Black Screen after login?

[devnulljp]

I've heard about the infamous black screen, but never encountered it until today.
Sat down to work on my (admittedly old) Thinkpad, running Ubuntu 17.04. It's been working more or less fine until today.
After login, I see my desktop wallpaper for a second, then just a black screen.
No panel, nothing. The system is running fine, and I can run things from the command line after hitting F2 and launching a konsole terminal.
But, obviously this is a problem.

I tried restarting the display manager service but it doesn't help

sudo systemctl restart display-manager.service

[GreyGeek]

If the display manger is running then try
startkde

[eddieg538]

Do you have an nvidia card? It's been a curse and nightmere to have an nvidia graphics card and kubuntu for years now, since about 2012. I can't install any kubuntu without using, nomodeset, even on the live cd. Now since the upgrade from 304.134 to 304.135 I experience screen flickering and jumping. It's irritating to say the least.

[oshunluvr]

If your desktop is running (ALT-F2 works) but not visible, I'd suspect user settings before I'd go mucking with the video driver. The process you're missing is "plasmashell". Look in ~/.xsession-errors to see if anything in there is relevant. Also try a different user (by adding one) or just log out, rename your home folder to something else and log back in allowing your home to rebuild with the defaults.

You can also try starting plasmashell manually - open a terminal using ALT-F2 to launch konsole. Then run plasmashell and see what happens.