I upgraded to 16.04 on my laptop today and encountered a weird problem: When I log in, the credential bars and the version number in the lower left disappear, just like it does when you usually log in. The problem is, my Desktop does not appear. Here's what I tried:

reinstalling nvidia drivers
reinstalling ubuntu-desktop unity
reinstalling xserver-xorg

What I found out is, that in the xsession_errors, there's pretty much only one error that is getting spammed until unity7 terminates for respawning too fast:

unity7 main process (70991) killed by SEGV signal

However, I could not find out where this segmentation fault occurs. Another weird thing is, that lspci tells me I am using the intel onboard graphics card instead of my GTX 950M, and I thought this might have something to do with it, so I tried reinstalling the nVidia drivers, but I could not get lspci to show that I am using an nVidia card.

using sudo systemctl restart lightdm I could get the desktop to show, but it flickers, the taskbar is not showing and after it stops flickering, I cannot use any keyboard input. I managed to open a terminal by rightclicking and pressing "open terminal here", but could not type anything.

How can I fix this?

Update: I managed to start the GUI (without taskbar) by restarting lightdm using the above command repeatedly, and afterwards I could type. Now the terminal is usable, but shortcuts (such as CTRL + ALT + T for opening the terminal) still don't work.


Okay, so I managed to fix this problem. Restarting OpenGL and its dependencies, aswell as Unity with the compizconfig-settings-manager did the trick.

I found this method here: https://askubuntu.com/a/76951/620612

Further testing revealed, that trying to switch tasks with the taskbar get unity to get more segmentation faults, making it flicker temporarily. It stops when I click somewhere else except the task bar though. Any thoughts?

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