KDE-Session crashes when configuring positions of multiple monitors

Bug #1306890 reported by kaefert on 2014-04-12
This bug affects 3 people
Affects Status Importance Assigned to Milestone
kde-workspace (Ubuntu)

Bug Description

I'm running Kubuntu 14.04 Beta2 on my Asus Zenbook UX32VD, which has an HDMI and an VGA output.

Most often when I try to configure the position of multiple monitors (by using the gui-tool `kcmshell4 kcm_kscreen`) the KDE-Session crashes with this error message:
"Could not start ksmserver. Check your installation."

It then takes a few reboots (as in more than 2 most of the times) to be able to login into a KDE Session with my user again, because it crashes again instantly when login in after such a crash. (Is there some config file I can edit/remove to work around this problem?

I've run into this problem about 5 or 6 times already, and I've never achieved a working setup where the multiple screens where interpreted as having a different y-position (in height, like for example above each other) but I also managed to get the same crash without y-position variations, by simply changing the x-position order (conrcrete from {default}[internal - hdmi - vga] to [vga - internal - hdmi] made KDE crash, while changing to [internal - vga - hdmi] worked.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: plasma-desktop 4:4.11.8-0ubuntu5
ProcVersionSignature: Ubuntu 3.13.0-23.45-generic 3.13.8
Uname: Linux 3.13.0-23-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu1
Architecture: amd64
CurrentDesktop: KDE
Date: Sat Apr 12 08:23:53 2014
InstallationDate: Installed on 2014-04-05 (6 days ago)
InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326.2)
SourcePackage: kde-workspace
UpgradeStatus: No upgrade log present (probably fresh install)

<-- my system is up to date, I've installed quite a few upgrades since my installation 6 days ago. I guess there's something wrong with this upgrade-log detection thingy..

kaefert (kaefert) wrote :
description: updated
description: updated
description: updated
description: updated
kaefert (kaefert) on 2014-04-12
summary: - KDE-Session crashes and shows "Could not start ksmserver. Check your
- installation." When configuring multiple monitors above each other
+ KDE-Session crashes when configuring positions of multiple monitors
description: updated
kaefert (kaefert) on 2014-04-12
description: updated
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in kde-workspace (Ubuntu):
status: New → Confirmed

I'm still seeing this bug still in my fully updated Ubuntu 16.04 alpha. I can recreate it every time.

When I start my laptop, it detects the external 2560x1080 external monitor and virtually places it to the right of the laptop screen. Since my laptop is physically to the right of the external monitor, I use systemsettings5/display configuration to drag it to the left of the virtual monitor. If I do that in one single step, I find that it always crashes the session as the original reported.

As a workaround, I've found I get the desired positioning in two steps by moving the external monitor to a virtual position /above/ the laptop screen, applying that, then moving the laptop screen to the right of the external monitor.

HOWEVER, if I restart the system after using that workaround, KDE will fail to start every time I login, and throw me back to lightDM. The only fix for that is to go to a terminal and delete the screen configuration in ~/.local/share/kscreen/. I then have to move the monitors around again after logging in; I do this every reboot. :\

There's nothing obviously wrong with the "bad" kscreen configuration that prevents login. I've attached it anyway - in case a dev can see where loading it would break things.

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