[Software] SDDM crashes resuming from Sleep?

[Snowhog]

I assume that is what's happening. I put the PC to Sleep, sometimes with Firefox open; most of the time with any running application closed. When I have the PC resume from Sleep; pressing any key; sometimes all I get is a black screen with a functioning mouse; the cursor moves. This happens several times a month.

I reboot using the Magic Key Sequence: Alt+Prnt+REISUB; and I am able to log in just fine. How can I diagnose this? Is SDDM actually crashing? Can I do something to restart it without having to do the clean process shutdown and reboot?

[die.boer]

when it happens again ,after reboot check logs

journalctl -b -1 -p 3

Look for:GPU errors , kwin crashes , segfaults

also , to see if it is actually SDDM...when it happens again,switch to TTY
If you get a login prompt,your system is alive...not SDDM
If TTY is also dead...deeper kernel/GPU issue

[die.boer]

Try recovering without reboot
When it happens: Restart your graphical session (not full reboot)
From TTY:

systemctl restart display-manager

This restarts SDDM, logging you out but avoiding a full reboot.

[wonder]

I assume that is what's happening. I put the PC to Sleep, sometimes with Firefox open; most of the time with any running application closed. When I have the PC resume from Sleep; pressing any key; sometimes all I get is a black screen with a functioning mouse; the cursor moves. This happens several times a month.

I reboot using the Magic Key Sequence: Alt+Prnt+REISUB; and I am able to log in just fine. How can I diagnose this? Is SDDM actually crashing? Can I do something to restart it without having to do the clean process shutdown and reboot?

What GPU do you have and what kernel version?
I had a similar problem, and it was the combination of GPU and that kernel...

[srllucas]

I have an issue with KDE + Wayland (X11 works normally), and I don’t know if it’s related to this topic. I can’t run any recent KDE + Wayland distribution. After the splash screen, the monitor goes to sleep. The system itself is still running — for example, I can access it through TTY (and the monitor wakes up again after switching to a TTY). In KDE, there is no active display in $DISPLAY. GNOME works normally, and I’m currently using Ubuntu for the reason I explained here (even though I love Kubuntu!).

System:
Host: luciano-X99-B9 Kernel: 7.0.0-15-generic arch: x86_64 bits: 64
Desktop: GNOME v: 50.1 Distro: Ubuntu 26.04 (Resolute Raccoon)
Machine:
Type: Desktop Mobo: MACHINIST model: X99 B9 serial: <superuser required>
Firmware: UEFI vendor: American Megatrends v: 5.11 date: 06/07/2024
CPU:
Info: 14-core Intel Xeon E5-2680 v4 [MT MCP] speed (MHz): avg: 1200
min/max: 1200/3300
Graphics:
Device-1: Advanced Micro Devices [AMD/ATI] Ellesmere [Radeon RX
470/480/570/570X/580/580X/590] driver: amdgpu v: kernel
Display: wayland server: X.Org v: 24.1.10 with: Xwayland v: 24.1.10
compositor: gnome-shell driver: dri: radeonsi gpu: amdgpu
resolution: 1920x1080~60Hz
API: OpenGL v: 4.6 compat-v: 4.5 vendor: amd mesa v: 26.0.3-1ubuntu1
renderer: AMD Radeon RX 570 Series (radeonsi polaris10 ACO DRM 3.64
7.0.0-15-generic)
Info: Tools: api: eglinfo, glxinfo, vulkaninfo gpu: corectrl x11: xdriinfo,
xdpyinfo, xprop, xrandr
Network:
Device-1: Realtek RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet
driver: r8169
Drives:
Local Storage: total: 1.35 TiB used: 63.36 GiB (4.6%)
Info:
Memory: total: 64 GiB available: 61.63 GiB used: 3.44 GiB (5.6%)
Processes: 497 Uptime: 25m Shell: Bash inxi: 3.3.40

[die.boer]

and I don’t know if it’s related to this topic.

prolly better to start a new topic

[wonder]

I have an issue with KDE + Wayland (X11 works normally), and I don’t know if it’s related to this topic. I can’t run any recent KDE + Wayland distribution. After the splash screen, the monitor goes to sleep. The system itself is still running — for example, I can access it through TTY (and the monitor wakes up again after switching to a TTY). In KDE, there is no active display in $DISPLAY. GNOME works normally, and I’m currently using Ubuntu for the reason I explained here (even though I love Kubuntu!).

System:
Host: luciano-X99-B9 Kernel: 7.0.0-15-generic arch: x86_64 bits: 64
Desktop: GNOME v: 50.1 Distro: Ubuntu 26.04 (Resolute Raccoon)
Machine:
Type: Desktop Mobo: MACHINIST model: X99 B9 serial: <superuser required>
Firmware: UEFI vendor: American Megatrends v: 5.11 date: 06/07/2024
CPU:
Info: 14-core Intel Xeon E5-2680 v4 [MT MCP] speed (MHz): avg: 1200
min/max: 1200/3300
Graphics:
Device-1: Advanced Micro Devices [AMD/ATI] Ellesmere [Radeon RX
470/480/570/570X/580/580X/590] driver: amdgpu v: kernel
Display: wayland server: X.Org v: 24.1.10 with: Xwayland v: 24.1.10
compositor: gnome-shell driver: dri: radeonsi gpu: amdgpu
resolution: 1920x1080~60Hz
API: OpenGL v: 4.6 compat-v: 4.5 vendor: amd mesa v: 26.0.3-1ubuntu1
renderer: AMD Radeon RX 570 Series (radeonsi polaris10 ACO DRM 3.64
7.0.0-15-generic)
Info: Tools: api: eglinfo, glxinfo, vulkaninfo gpu: corectrl x11: xdriinfo,
xdpyinfo, xprop, xrandr
Network:
Device-1: Realtek RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet
driver: r8169
Drives:
Local Storage: total: 1.35 TiB used: 63.36 GiB (4.6%)
Info:
Memory: total: 64 GiB available: 61.63 GiB used: 3.44 GiB (5.6%)
Processes: 497 Uptime: 25m Shell: Bash inxi: 3.3.40

As others have mentioned, it's best to start a new thread. In any case, you should specify the kernel version and driver.
What happened to me was specifically a kernel issue with Polaris; changing the kernel version fixed it. I wasn't using Wayland (I just tried it on a Kubuntu 26.04 installation, but I had to revert to X11).

[skyfishgoo]

expecting wayland to work on 24.04 is a fools errand... just use X11 until you upgrade to 26.06 where most of these issues have been ironed out.

[Snowhog]

I believe I 'solved' this issue. Since creating the delay for SDDM startup, I haven't experienced the problem (fingers crossed).

AI Overview

To fix the black screen with a moving cursor on the SDDM login screen after resuming from sleep, you can introduce a brief delay to allow your graphics drivers to wake up properly before the display manager reinitializes. This timing issue usually occurs because the display server attempts to start before the GPU is fully initialized.

You can resolve this by using systemctl edit to add a startup delay to the SDDM service or by restarting the display manager via systemd suspend scripts.

Delay SDDM Startup

Adding a 2 to 5-second delay to the SDDM service gives your GPU enough time to initialize after wake-up.

1. Open your terminal and edit the SDDM service configuration:

sudo systemctl edit sddm.service

2. Your terminal will open a text editor. Add the following lines in the [Service] section (make sure to keep the # comments at the top if any, and add the override block below them): ini

[Service] ExecStartPre=/usr/bin/sleep 4

3. Save and close the file (if using nano, press Ctrl+O, Enter, then Ctrl+X).

4. Reload systemd to apply the changes:

sudo systemctl daemon-reload

[Snowhog]

I believe I 'solved' this issue. Since creating the delay for SDDM startup, I haven't experienced the problem (fingers crossed).

Well, it sorta happened again just a few minutes ago, but this time I had the SDDM Login background image displayed, but not the input area. Used the MAGIC Key sequence to safely shutdown/restart the PC.

[wonder]

Well, it sorta happened again just a few minutes ago, but this time I had the SDDM Login background image displayed, but not the input area. Used the MAGIC Key sequence to safely shutdown/restart the PC.

That's a shame, I thought you'd been able to solve it. When I had the other problem, I tried very similar tests to yours. Let's hope I get lucky and it can be fixed...