Lock screen hangs

[alex55]

Hi there,

I have installed the latest updates to my laptop under KDE Neon and since that the lock screen hangs every time.

Usually it hangs after the lock screen appeared, for example after I press Meta+L that is binded to invoke lock screen, before turn off the display. Even clock is being stopped on the lock screen. Rarely it hangs after the display has turned off. Anyway, I can’t unlock my laptop anymore and have to reboot it. However, if I press CapsLock or Microphone mute button, I see that my laptop reacts with turning on/off LEDs on the according buttons. Also I can login via ssh to the laptop and reboot it. So, it seems that the base system is still operable.

What can i do to debug the problem? There are no core dumps because the app just hangs, but not crashes.

I have tryed to update my system once again, but pkcon update says there are no new updates.

[alex55]

If it helps, i’ve found these messages in log files:

$ sudo grep -i screenlock /var/log/syslog
2025-12-21T04:12:06.107968+04:00 laptop dbus-daemon[1200]: [system] Activating via systemd: service name=‘net.reactivated.Fprint’ unit=‘fprintd.service’ requested by ‘:1.149’ (uid=1000 pid=76193 comm=“/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet” label=“unconfined”)
2025-12-21T04:12:09.474133+04:00 laptop kscreenlocker_greet[76193]: Could not create EGL surface (EGL error 0x3000)
2025-12-21T04:12:09.519217+04:00 laptop kscreenlocker_greet[76193]: Failed to write to the pipe: Bad file descriptor.
2025-12-21T05:47:57.867793+04:00 laptop dbus-daemon[1200]: [system] Activating via systemd: service name=‘net.reactivated.Fprint’ unit=‘fprintd.service’ requested by ‘:1.184’ (uid=1000 pid=81375 comm=“/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet” label=“unconfined”)
2025-12-21T05:48:03.393654+04:00 laptop kscreenlocker_greet[81375]: Could not create EGL surface (EGL error 0x3000)
2025-12-21T05:48:03.428141+04:00 laptop kscreenlocker_greet[81375]: Failed to write to the pipe: Bad file descriptor.
2025-12-21T09:46:04.573545+04:00 laptop dbus-daemon[1199]: [system] Activating via systemd: service name=‘net.reactivated.Fprint’ unit=‘fprintd.service’ requested by ‘:1.178’ (uid=1000 pid=18512 comm=“/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet” label=“unconfined”)
2025-12-21T09:46:09.102784+04:00 laptop kscreenlocker_greet[18512]: Could not create EGL surface (EGL error 0x3000)
2025-12-21T09:46:09.135660+04:00 laptop kscreenlocker_greet[18512]: Failed to write to the pipe: Bad file descriptor.
2025-12-21T11:55:06.374302+04:00 laptop dbus-daemon[1199]: [system] Activating via systemd: service name=‘net.reactivated.Fprint’ unit=‘fprintd.service’ requested by ‘:1.186’ (uid=1000 pid=19183 comm=“/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet” label=“unconfined”)
2025-12-21T11:55:10.630988+04:00 laptop kscreenlocker_greet[19183]: Could not create EGL surface (EGL error 0x3000)
2025-12-21T11:55:10.674740+04:00 laptop kscreenlocker_greet[19183]: Failed to write to the pipe: Bad file descriptor.

[ostfriese4]

I had the same issue maybe one or two weeks ago. It seems to be fixed already, for I’m no longer experiencing it. Executing kwin_wayland --replace using ssh or KDE Connect fixed it.

[alex55]

@ostfriese4

It seems to be fixed already

Unfortunately, just restarted my laptop after the screenlock hangs again.

[alex55]

2025-12-21T16:54:30.446395+04:00 laptop kwin_wayland[2016]: Atomic modeset test failed! Invalid argument
2025-12-21T16:54:30.446568+04:00 laptop kwin_wayland[2016]: Setting dpms mode failed!

Looks like it’s the same problem that is described here:

Turn screen off settings in power causing issues with Plasma 6.5.4

This seems to have started after I updated plasma. When the screen goes to turn off it seems to just dim but then locks completely. I have to close the lid of my laptop so that it goes to sleep and then open it up again to have it force the log in screen to get my laptop to be accessible again. It only seems to be an issue though is the screen is first dimmed and then the screen shuts off. If I have the dim and shutoff both set to the same time I’ve got no issue. Anyone else see this issue?

[alex55]

According to release schedule page Schedules/Plasma 6 - KDE Community Wiki , KDE Neon 6.5.5 with the fix is going to be released in a month from now.

Is it possible to roll back the update and get back to 6.5.3?

[alex55]

KDE 6.5.5 has been released. It solved the issue.

[happycthulhu]

Can verify this. Since the update I’m no longer seeing the issue.