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charged

Member

From: Ontario

Registered: 2025-06-06

Posts: 10

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Plasma Wayland won't launch

Title. After logging in through SDDM it just black screens and my monitor turns off automatically as it no longer detects anything. This issue doesn't happen with Hyprland or Sway on Wayland, and Plasma works fine under X11.
Trying to run `dbus-run-session  startplasma-wayland` in a TTY outputs nothing.
I ran `journalctl -u sddm` and didn't find much other than the following:

Jul 29 15:20:00 surge sddm-helper\[124720\]: Starting Wayland user session: "/usr/share/sddm/scripts/wayland-session" "/usr/lib/plasma-dbus-run-session-if-needed /usr/bin/startplasma-wayland"

Jul 29 15:20:00 surge sddm\[917\]: Session started true

Jul 29 15:20:29 surge sddm\[917\]: Auth: sddm-helper exited with 64

Any help would be much appreciated.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,076

Re: Plasma Wayland won't launch

The full journal without an sddm filter would probably give more insight:

sudo journalctl -b | curl -F 'file=@-' 0x0.st

There recently has been a change in how kscreen tries to identify unique screens, maybe something bites itself with your specific setup.

charged

Member

From: Ontario

Registered: 2025-06-06

Posts: 10

Website

Re: Plasma Wayland won't launch

The full journal without an sddm filter would probably give more insight:

sudo journalctl -b | curl -F 'file=@-' 0x0.st

There recently has been a change in how kscreen tries to identify unique screens, maybe something bites itself with your specific setup.

https://0x0.st/8R4a.txt is my output I wasn't able to find much but maybe it has more info that could help.

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,629

Re: Plasma Wayland won't launch

That log has you starting hyprland?

charged

Member

From: Ontario

Registered: 2025-06-06

Posts: 10

Website

Re: Plasma Wayland won't launch

That log has you starting hyprland?

Yeah I launched hyprland after plasma failed to use my computer and all, I dunno if a reboot resets the log.

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,629

Re: Plasma Wayland won't launch

-b specifically returns the journal from the current boot. If you need the log from a previous boot, you need to give it the number of that boot. See https://man.archlinux.org/man/journalct … NG_OPTIONS

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,076

Re: Plasma Wayland won't launch

And are you sure you're frozen to the point that a Ctrl+Alt+F2...F9 wouldn't bring you to a still working VT?

charged

Member

From: Ontario

Registered: 2025-06-06

Posts: 10

Website

Re: Plasma Wayland won't launch

And are you sure you're frozen to the point that a Ctrl+Alt+F2...F9 wouldn't bring you to a still working VT?

After Plasma fails and it goes back to SDDM, I can't launch any desktop session, it just freezes.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,076

Re: Plasma Wayland won't launch

That combinations of buttons should bring you to a different VT (...virtual terminal, a full screen terminal like you might have seen during installation) regardless of what is happening on SDDM/with Plasma, if it's a wayland start chances are plasma will take VT2 but F3 to F8 should still be an option.

Anyway with either this or the previous boot filter method, is it possible to procure a proper log showing the failure? Also how do you "reboot" when in this situation? If you press the power button to hard reset that might not be good for getting logs, in which case you should first try whether frantically hammering Ctrl+Alt+Delete (you just have to hammer the delete) which will invoke a "safe" reboot given systemd and the kernel can still react. If that isn't possible try the REISUB sequence, once enabled via one of the shown methods this should almost always allow you to somewhat safely reboot.

workonfire

Member

Registered: 2025-08-04

Posts: 3

Re: Plasma Wayland won't launch

Hello.
I have the exact same issue. The monitor simply goes to sleep mode after trying to log in into KDE Wayland.
I also tried changing the SDDM display server from Xorg to Wayland and the issue persists; the monitor doesn't go to sleep mode - it just shows a black screen.
I'm unable to enter any VT and I'm forced to reboot.
Here's the journal from my current boot (by manually invoking startplasma-wayland, which works fine) and from the failed SDDM boot: https://0x0.st/8h-f.txt

Aug 04 15:00:08 wzium-msi systemd[1]: Stopping Session 2 of User krystian...
Aug 04 15:00:08 wzium-msi login[839]: pam_unix(login:session): session closed for user krystian
Aug 04 15:00:08 wzium-msi sddm-helper[678]: Signal received: SIGTERM
Aug 04 15:00:08 wzium-msi sddm-greeter-qt6[709]: Signal received: SIGTERM
Aug 04 15:00:08 wzium-msi sddm-helper-start-wayland[692]: Signal received: SIGTERM
Aug 04 15:00:08 wzium-msi sddm-helper-start-wayland[692]: quitting helper-start-wayland
Aug 04 15:00:08 wzium-msi sddm-helper-start-wayland[692]: Stopping... "/usr/bin/sddm-greeter-qt6"
Aug 04 15:00:08 wzium-msi systemd[1]: Stopping Session c1 of User sddm...
Aug 04 15:00:08 wzium-msi sddm[675]: Error from greeter session: "Process crashed"
Aug 04 15:00:08 wzium-msi sddm[675]: Auth: sddm-helper (--socket /tmp/sddm-auth-0ea9a20b-831d-4196-badb-6203b14d856c --id 2 --start /usr/bin/sddm-greeter-qt6 --socket /tmp/sddm--BEbRxV --theme /usr/share/sddm/themes/silent --user sddm --display-server weston --shell=kiosk --greeter) crashed (exit code 1)
Aug 04 15:00:08 wzium-msi sddm[675]: Error from greeter session: "Process crashed"
Aug 04 15:00:08 wzium-msi sddm[675]: Auth: sddm-helper exited with 1
Aug 04 15:00:08 wzium-msi sddm[675]: Greeter stopped. SDDM::Auth::HELPER_AUTH_ERROR
Aug 04 15:00:08 wzium-msi systemd[1]: Removed slice Slice /system/dbus-:1.2-org.kde.kded.smart.
Aug 04 15:00:08 wzium-msi systemd[1]: Removed slice Slice /system/dbus-:1.2-org.kde.powerdevil.backlighthelper.
Aug 04 15:00:08 wzium-msi systemd[1]: Removed slice Slice /system/dbus-:1.2-org.kde.powerdevil.chargethresholdhelper.
Aug 04 15:00:08 wzium-msi systemd[1]: Removed slice Slice /system/dbus-:1.2-org.kde.powerdevil.discretegpuhelper.
Aug 04 15:00:08 wzium-msi systemd[1]: Removed slice Slice /system/modprobe.
Aug 04 15:00:08 wzium-msi systemd[1]: Stopped target Graphical Interface.
Aug 04 15:00:08 wzium-msi systemd[1]: Stopped target Multi-User System.
Aug 04 15:00:08 wzium-msi systemd[1]: Stopped target Login Prompts.
Aug 04 15:00:08 wzium-msi systemd[1]: Stopped target Sound Card.
Aug 04 15:00:08 wzium-msi systemd[1]: Stopped target Timer Units.

Last edited by workonfire (2025-08-04 13:09:37)

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 73,703

Re: Plasma Wayland won't launch

I have the exact same issue. The monitor simply goes to sleep mode after trying to log in into KDE Wayland.

Can you still log into kde/X11 or just openbox ?
Can you log into kde/wayland from eg. lightdm ?

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workonfire

Member

Registered: 2025-08-04

Posts: 3

Re: Plasma Wayland won't launch

I have the exact same issue. The monitor simply goes to sleep mode after trying to log in into KDE Wayland.

Can you still log into kde/X11 or just openbox ?
Can you log into kde/wayland from eg. lightdm ?

Hello. I'm sorry for the delay.

I can't log in into any session. KDE Wayland shows a black screen, KDE X11 and Openbox just throw me back into SDDM.
I tried using ly, but a similar thing happens - every session just throws me back to the login screen, even when I try logging into the shell with ly.
And LightDM doesn't even wanna start:

$ systemctl status lightdm

lightdm.service - Light Display Manager
    Loaded: loaded (/usr/lib/systemd/system/lightdm.service; enabled; preset: disabled)
    Active: failed (Result: exit-code) since Sat 2025-08-16 20:06:26 CEST; 1min 36s ago
Invocation: 322ed9b91b57467aaf188a25a290abf3
      Docs: man:lightdm(1)
   Process: 705 ExecStart=/usr/bin/lightdm (code=exited, status=1/FAILURE)
  Main PID: 705 (code=exited, status=1/FAILURE)

Aug 16 20:06:26 wzium-msi systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
Aug 16 20:06:26 wzium-msi systemd[1]: lightdm.service: Start request repeated too quickly.
Aug 16 20:06:26 wzium-msi systemd[1]: lightdm.service: Failed with result 'exit-code'.
Aug 16 20:06:26 wzium-msi systemd[1]: lightdm.service: Failed to start Light Display Manager.

However, I'm able to launch any session I want on a new user I made through the KDE Settings.
I'm not even sure how I can properly diagnose this.

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 73,703

Re: Plasma Wayland won't launch

Your lightdm and matching xorg logs are in /var/log and might shed more light on this.

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workonfire

Member

Registered: 2025-08-04

Posts: 3

Re: Plasma Wayland won't launch

Thank you. I was able to fix lightdm not starting (I didn't read the wiki, I know nothing about lightdm but I thought I could just install it and enable it; turns out I was missing a greeter).
None of the logs provided any valuable info, but I was able to fix the issue by removing the ~/.Xauthority file.
Now SDDM works as expected!

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 73,703

Re: Plasma Wayland won't launch

\o/
Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

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