I have a dell xp13 with the latest Kubuntu. I used to work fine when I plugged in my external screen or a projector (I give presentations all the time).
Now all of a sudden (I think I might have been pressing a key when I plugged in the screen) both of the screens turn black when I plug in the thunderbolt with vga or hdmi and I see my mouse in on the left side of the external screen and can move it up and down (no other movement).
I tried pressing Fn-F8, but to no avail. Is there anything I can check (error log?) or do? I normally use kscreen to configure the displays, but since the screen is black I can't do anything after plugging it in.
update–
I noticed the screen cable doesn't even need to be plugged in. As soon as I plug in the thunderbolt adapter, the laptop screen goes black. I unplug it and the laptop screen comes back.
update2– all of a sudden it worked. Then it broke again, I was just working with INScore, and browsing the web. My cursor first dissapeared. I rebooted and the screen problem was back. Rebootet about 5 times already and still persists. As soon as I plug the thunderbolt in, screen fades to black…
Any log file I could check?
Thanks for any help!
–update:
I see this in /var/log/Xorg.0.log. I think this looks normal no? Or am I missing something…
[ 16611.424] (II) intel(0): switch to mode 1024x768@60.0 on DP1 using pipe 0, position (3200, 720), rotation normal, reflection none
[ 16617.756] (II) intel(0): switch to mode 3200x1800@60.0 on eDP1 using pipe 0, position (0, 0), rotation normal, reflection none
–update2
I just logged in as system admin to kde and it seemed to work. However, logging in as my regular user, same problem. Could it be a settings file specific to the user somewhere?
Also found this in the log file:
5.688] (II) intel(0): Output DP1 has no monitor section
5.688] (II) intel(0): Enabled output DP1
Best Answer
Compositor seems to have an influence on this (at least for me). I've made sure the compositor was enabled on startup. And switched from openGL3.1 to 2.0. This made a difference but caused some screen flickering. XRender seemed to works lightly better. Sometimes it does still happen but a reboot seems to fix it when that setting is set.
I also created a new user and it worked fine with the new user.
--update: final solution: After deleting the kscreen folder in .config, and all files starting with plasma, things worked out for me. There is an official bug report about this here.