Cannot login after long AFK at lock screen with monitor off

Hi there,

I installed CachyOS ~1 week ago, and did not updated or turned off my computer for a week. And during the week, I used my computer as usual, where I would just lock the desktop (meta+L) and then turn off my monitor (with the power button of the monitor) if I need to leave the computer. The reason I don’t turn my computer off (or let it sleep) is because I usually have to run some long lasting jobs (e.g. machine learning).

A two days ago, I finally decided to update and reboot my system. It seems like multiple things have updated at the same time: nvidia driver, plasma, the kernal, etc. After the update, I noticed that when I power on/off my monitor, the system would play a “system bell” sound (the same sound you would hear when you plug in an USB device), which was not the case before I update the system.

This may not be related to my main issue. The issue was that if I lock my screen and power off my screen for a long time (e.g. >10 mins), when I come back, turn back on my screen, enter my password, and hit enter, nothing would happen: no black screen, would no enter plasma, even clicking “>” button next to the password box would not do anything either. However, if I click “Switch User”, it would go to the login screen (SDDM). If I enter my password there, it would give me a black screen and my monitor would say there’s no signal.

Note that this does NOT happen, if I lock my screen, turn off my monitor for a SHORT time (say ~1 min) and turn it back on, it would enter plasma if I enter my password from the lock screen (the system bell sound would still play).

The reason why I mentioned the “system bell” sound when I power on/off my monitor is that I am guessing that maybe plasma “disconnects” my monitor when I powered it off, and after a long AFK, plasma “cannot find” my monitor anymore so that’s why it lost its signal… I could be completely wrong and it could just be a stupid nvidia driver thing…

Again, this was NOT the behavior before the update, I would not hear the “system bell” sound, neither was there any issue with login after long AFK.

Some extra information that may help pinpoint the issue:

  • Kernal: 6.11.4-2-cachyos
  • Nvidia-driver: 560.35.03-16
  • Plasma: 6.2.1.1-1.1

If anyone has any insight about this issue, it would be greatly appreciated. Thank you in advance.

Based on the OP, it looks like you can access the system, so the next step would be to enter TTY3 (CTRL + ALT + F3) and try running startplasma-wayland. Getting some logs would be helpful too sudo cachyos-bugreport.sh

Thanks for the quick response. And yes you are right, I was able to enter different TTYs, including TTY3. I did not know about the command startplasma-wayland but I will try it next time I encounter this issue.

For the logs, should I run sudo cachyos-bugreport.sh before the issue happens, or after? (Sorry for the stupid question.)

You should run it after.

Thanks again for your patience and assistance on helping me out.

I found a work-around to my problem, where I could “turn off screen” (it’s actually making the monitor go to sleep) immediately after lock, in System Settings → Power Management:

This does not “disconnect” my monitor (no system bell played) when I lock my screen. And I don’t need to use the power button on my monitor in this way. I just need to make sure I don’t accidentally move my mouse that wakes up the screen.

Update: My previous work-around did not solve the problem, it happened again just now: I left my PC locked for >2 hours, and again, cannot enter plasma when I enter my password.

I switched to TTY3 and ran sudo cachyos-bugreport.sh. Wiredly, when I ran the command, TTY3 also lost monitor signal, but when I switched back to TTY2, it entered the plasma desktop…

Nevertheless, I was able to obtain the bug report from where I ran the command. Due to word limit and file upload limitation here, I uploaded the log file to my github, if you would like to take a look: cachyos-bugreport.log

Hope this is useful. Thanks in advanced for any help you could offer.