Screen Turns on After Being Turned Off by Power Management

Help
1

Need some help.

Since upgrading to 6.4 (this might also be a kernel issue as I updated that around the same time), some time after KDE turns off the screen per my Power Management Settings, the screen comes back on and looks like this.

Normally the screen gets turned off and stays off, but every so often it does this instead. When it doesn’t do this, taping a key turns the screen back on, but, when this happens, the system is unresponsive to the keyboard and they only way I can use the system again is to pull the power (then the system switches to battery, the screen wakes up, and the keyboard works again).

Any idea how to troubleshoot/resolve? I don’t see anything of interest in dmesg to my untrained eyes.

Thanks.

KDE_Screen_On_After_Off
KDE_Screen_On_After_Off3072×3452 185 KB

2

A. Don’t use dmesg - this is the 21st century. Use journalctl -k and then some selector, like journalctl -k -b0 for all kernel messages since last boot, journalctl -k -S-1h for kernel messages in the last hour, or journalctl -kf to follow kernel messages.
B. I wouldn’t expect to see anything interesting in the kernel messages unless this is actually a hardware issue. More likely this is a kwin/kscreenlocker_greet issue. I would look in the user journal for kwin, with something like this:

journalctl --user -u plasma-kwin_wayland.service _COMM=kscreenlocker_g

and see if kscreenlocker_greet has some complaints.

3

Thanks for chiming in. While I agree that dmesg is legacy, my distribution doesn’t have systemd.

In reviewing my logs, I do see some complaints from kscreenlocker_greet, but I don’t know if they’re related:

2025-09-15T16:54:16.83629 authpriv.notice: Sep 15 10:54:16 kscreenlocker_greet: pam_unix(kde-fingerprint:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>
2025-09-15T16:54:19.27366 authpriv.notice: Sep 15 10:54:19 kscreenlocker_greet: pam_unix(kde-smartcard:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>
2025-09-15T19:11:06.20841 authpriv.notice: Sep 15 13:11:06 kscreenlocker_greet: pam_unix(kde-fingerprint:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>
2025-09-15T19:11:07.95335 authpriv.notice: Sep 15 13:11:07 kscreenlocker_greet: pam_unix(kde-smartcard:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>
2025-09-15T21:26:30.64051 authpriv.notice: Sep 15 15:26:30 kscreenlocker_greet: pam_unix(kde-fingerprint:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>
2025-09-15T21:26:32.70650 authpriv.notice: Sep 15 15:26:32 kscreenlocker_greet: pam_unix(kde-smartcard:auth): authentication failure; logname=<redacted> uid=<redacted> euid=<redacted> tty= ruser= rhost=  user=<redacted>

I don’t use a fingerprint or smartcard for authentication, so I’m not sure if this is to be expected.

5

Hey @guss77. I think you might be right with it not being a hardware issue. Since updating to 6.5.2, it appears the issue is gone.