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Topic: SDDM Cannot Launch Plasma-wayland Session (Read 3758 times) previous topic - next topic
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SDDM Cannot Launch Plasma-wayland Session

Background: Plasma DE (s6) with the relevant wayland packages (plasma-wayland-protocols, plasma-wayland-session, etc.) installed and SDDM as the greeter.

Problem: SDDM cannot launch a wayland session. If auto-login is enabled then the session does not start and the greeter appears (selecting wayland fails while X11 succeeds). When the greeter appears on boot (such as when auto-login is disabled) and you select plasma-wayland as the session, the screen  goes black and you are kicked back to the greeter.

Similar problems: 1. Here on the Artix forum. 2. Discussion on SDDM Github.

I am unsure of whether the reason in the first link is still relevant and I have tried some of the suggestions in the second link, but those were unsuccesful.

Launching a nested wayland session via
Code: [Select]
XDG_SESSION_TYPE=wayland dbus-run-session startplasma-wayland
executes without any problem.

Relevant information:
Code: [Select]
inxi -G
Graphics:
  Device-1: AMD Cezanne driver: amdgpu v: kernel
  Device-2: IMC Networks USB2.0 HD UVC WebCam type: USB driver: uvcvideo
  Display: x11 server: X.Org v: 21.1.4 with: Xwayland v: 22.1.3 driver: X:
    loaded: amdgpu unloaded: fbdev,modesetting,vesa gpu: amdgpu
    resolution: 2880x1800~90Hz
  OpenGL: renderer: AMD RENOIR (LLVM 14.0.6 DRM 3.46 5.18.10-artix1-1)
    v: 4.6 Mesa 22.1.3

SDDM wayland session log:
Code: [Select]
kdeinit5: preparing to launch '/usr/lib/kf5/klauncher'
kdeinit5: Launched KLauncher, pid = 11626, result = 0

(kwin_wayland:11616): Gtk-WARNING **: 10:25:43.290: cannot open display:

(kwin_wayland:11627): Gtk-WARNING **: 10:25:43.446: cannot open display:

/** TRUNCATED: the above line is repeated several times **/

qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
The Wayland connection broke. Did the Wayland compositor die?
qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
The Wayland connection broke. Did the Wayland compositor die?
kdeinit5: Communication error with launcher. Exiting!
Error: could not determine $DISPLAY.
Error: Can not contact kdeinit5!
org.kde.startup: "kdeinit5_shutdown" () exited with code 255
startplasma-wayland: Shutting down...
startplasmacompositor: Shutting down...
startplasmacompositor: Done.

The sddm-git AUR package has the same behaviour.

Has anybody faced this problem and managed to solve it?

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #2 –
I guess that this may have been related to a Calamares install, though I am not sure. After a new base install, and installing the relevant packages (in the same way as before), plasma-wayland launches without a problem.  Marking as solved.

Re: [Solved] SDDM Cannot Launch Plasma-wayland Session

Reply #3 –
I have the same issue, and reinstalling from base isn't really an option for me. I also have an AMD GPU, and I've tried just about everything I can think of.

Just like OP, a nested session works fine. Launching from SDDM does not, even if I have SDDM-git installed. The elogind service is enabled and runs at boot (although it was not enabled by default), and I even tried manually exporting XDG_RUNTIME_DIR in both the sddm wayland script, as well as the sddm runit service. I also cannot manually start the session from a tty, as suggested in some other posts. Nothing I've tried works.

My error log is the same as OP's, and not even exporting the display manually works. I'm really not sure what's going on here.

What is different about installing from the base image vs installing from Calamares? Is there a config file or something missing from a Calmares install that I can simply add to my own install?

Maybe this should be un-marked as solved until this gets more attention? "Reinstall from a base iso to fix an issue no one knows the cause of" isn't much of a solution  :P

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #4 –
Perhaps you are right. This may require a definitive solution and not the one which led me to initially mark this as solved (now unsolved at present). Hopefully we can determine why this problem exists, so that future users will no longer face it.

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #5 –
I recommend you to install a syslog implement such as metalog to get more information.

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #6 –
I got the exact same issue, I just reinstalled artix and forget how to fix it

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #7 –
I think I got something but need someone to verify...

All I did was rename my /etc/environment to /etc/environment.bak
Now it seems I can log into Wayland from SDDM.
Can someone replicate this? 

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #9 –
@Hitman, The only two lines in my /etc/environment were as follows...
Code: [Select]
QT_STYLE_OVERRIDE=gtk2
QT_QPA_PLATFORMTHEME=gtk

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #10 –
Oh, these are the defaults in at least some variants for uniform Qt styling.
It must be QT_STYLE_OVERRIDE that conflicts with kde's qt plugin, you probably don't need it at all as it only affects very few programs that don't get themed the conventional way with platformtheme, so remove it from there. :-)

Re: SDDM Cannot Launch Plasma-wayland Session

Reply #11 –
Quote from: HighBridge – on
I think I got something but need someone to verify...

All I did was rename my /etc/environment to /etc/environment.bak
Now it seems I can log into Wayland from SDDM.
Can someone replicate this? 
Replicated with success, I now can login under wayland thanks

Cannot login into Wayland session through SDDM.

Reply #12 –
Hello, I cannot log in to a wayland session using sddm. It just shows blank screen and goes back to the login screen. Though, I can login into Wayland using command:
 dbus-run-session startplasma-wayland

Using command:
cat ~/.local/share/sddm/wayland-session.log
I got following log:
Code: [Select]
dbus-daemon[25371]: [session uid=1000 pid=25371] Activating service name='org.kde.KSplash' requested by ':1.0' (uid=1000 pid=25372 comm="/usr/bin/startplasma-wayland")
dbus-daemon[25371]: [session uid=1000 pid=25371] Activating service name='org.freedesktop.portal.Desktop' requested by ':1.4' (uid=1000 pid=25385 comm="/usr/bin/ksplashqml")
kdeinit5: preparing to launch '/usr/lib/kf5/klauncher'
kdeinit5: Launched KLauncher, pid = 25394, result = 0
dbus-daemon[25371]: [session uid=1000 pid=25371] Activating service name='org.freedesktop.portal.Documents' requested by ':1.5' (uid=1000 pid=25392 comm="/usr/lib/xdg-desktop-portal")
dbus-daemon[25371]: [session uid=1000 pid=25371] Activating service name='org.freedesktop.impl.portal.PermissionStore' requested by ':1.6' (uid=1000 pid=25399 comm="/usr/lib/xdg-document-portal")
dbus-daemon[25371]: [session uid=1000 pid=25371] Successfully activated service 'org.freedesktop.impl.portal.PermissionStore'
dbus-daemon[25371]: [session uid=1000 pid=25371] Successfully activated service 'org.freedesktop.portal.Documents'
fusermount3: failed to access mountpoint /run/user/1000/doc: Permission denied
error: fuse init failed: Can't mount path /run/user/1000/doc
dbus-daemon[25371]: [session uid=1000 pid=25371] Activating service name='org.freedesktop.impl.portal.desktop.gtk' requested by ':1.5' (uid=1000 pid=25392 comm="/usr/lib/xdg-desktop-portal")

(kwin_wayland:25382): Gtk-WARNING **: 23:24:57.548: cannot open display: 

(kwin_wayland:25424): Gtk-WARNING **: 23:24:57.626: cannot open display: 

(kwin_wayland:25428): Gtk-WARNING **: 23:24:57.703: cannot open display: 

(kwin_wayland:25430): Gtk-WARNING **: 23:24:57.783: cannot open display: 

(kwin_wayland:25432): Gtk-WARNING **: 23:24:57.859: cannot open display: 

(kwin_wayland:25434): Gtk-WARNING **: 23:24:57.936: cannot open display: 

(kwin_wayland:25436): Gtk-WARNING **: 23:24:58.013: cannot open display: 

(kwin_wayland:25438): Gtk-WARNING **: 23:24:58.089: cannot open display: 

(kwin_wayland:25440): Gtk-WARNING **: 23:24:58.165: cannot open display: 

(kwin_wayland:25442): Gtk-WARNING **: 23:24:58.243: cannot open display: 

(kwin_wayland:25444): Gtk-WARNING **: 23:24:58.322: cannot open display: 
The Wayland connection broke. Did the Wayland compositor die?
The Wayland connection broke. Did the Wayland compositor die?
kdeinit5: Communication error with launcher. Exiting!
Error: could not determine $DISPLAY.
Error: Can not contact kdeinit5!
org.kde.startup: "kdeinit5_shutdown" () exited with code 255
startplasma-wayland: Shutting down...
startplasmacompositor: Shutting down...
startplasmacompositor: Done.

Has anybody any ideas what caused this? I have AMD card not Nvidia (https://forum.endeavouros.com/t/plasma-wayland-session-cant-login/36613.)

Re: Cannot login into Wayland session through SDDM.

Reply #13 –
possible duplicate of this post