[SRU] KDE does not start when using lightdm

Hello, thanks for reporting this, but in order to properly triage this, I need more information.

How exactly did you install LightDM? Did you remove SDDM after installing LightDM?

And most importantly, is this still an issue for you?

This looks awfully similar to a bug I've seen before, so for now I'm marking as Incomplete, but if this still affects you, please change it back to New.

Thanks for making Kubuntu better! :)

Hi Simon,

> How exactly did you install LightDM? Did you remove SDDM after installing LightDM?
I did not remove SDDM after the installation of LightDM and just ran the configuration and set LightDM as default.

At the moment it is not really an issue for us, as we apply the above mentioned workaround:

$ cat /usr/share/lightdm/lightdm.conf.d/40-kde-plasma-kf5.conf
[SeatDefaults]
user-session=kde-plasma-kf5

Let me know if you need further information.

Thanks
Thomas

[Expired for plasma-workspace (Ubuntu) because there has been no activity for 60 days.]

2020 and still not fixed, thanks for solution

I ran into the same problem in 20.04 after switching to lightdm and it took me a while to figure out.

Just as Simon pointed out:
/usr/share/lightdm/lightdm.conf.d/40-kde-plasma-kf5.conf
should have:
user-session=plasma
instead of
user-session=kde-plasma-kf5
since there is no kde-plasma-kf5.desktop in /usr/share/xsessions

I understand that most people aren't switching the display manager but this is such an easy fix I'd hope that it's done to save a lot of frustration for the few that do.

This is still a problem in Ubuntu/Kubuntu & Linux mint with KDE.

Please fix this one liner!

Just chiming in to say that opensense's solution above also fixed it for me. I created /etc/lightdm/lightdm.conf and put in it:

[SeatDefaults]
user-session=plasma

and it worked to fix the "Failed to start session" error in the greeter after entering my password.

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

[ Impact ]

 * Switch to lightdm and plasma will not load.

[ Test Plan ]

 * Switch to plasma and lightdm will not load.

[ Where problems could occur ]

 * This only affects lightdm users.

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

Accepting, but please fix the Test Plan. These should be step by step instructions on how to reproduce the problem, and it should be possible for a developer not familiar with the package to follow the steps unambiguously. What is the starting point? Which method to "switch to plasma" should they use? What should they see if the test is successful, and what do they see when the test fails?

Hello Thomas, or anyone else affected,

Accepted plasma-workspace into noble-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/plasma-workspace/4:5.27.11-0ubuntu4.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-noble to verification-done-noble. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-noble. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

All autopkgtests for the newly accepted plasma-workspace (4:5.27.11-0ubuntu4.2) for noble have finished running.
The following regressions have been reported in tests triggered by the package:

systray-mdstat/1.2.0-2 (armhf)
systray-mdstat/unknown (s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/noble/update_excuses.html#plasma-workspace

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

These regressions are now fixed by rebuilds.

[ Test Plan ]

 * Switch to lightdm login manager. Without proposed package, plasma will fail to load.

 * Install proposed package. Plasma will now load.