I cannot get SDDM to show up. The splash screen shows up as normal, but I can neither start SDDM, nor the X server. When I boot in safe mode everything seems to work, but I specifically need the laptop for testing graphics performance of my apps, so that’s out of question.
The issue first started when I updated an old laptop to the newest Plasma with Ubuntu 24.4. I thought something broke since I haven’t updated it in quite a long time, so I redownloaded the image and launched the installation media. Same issue, GUI won’t show up. I could still install it by using the live image in safe mode. After installation of a fresh system the same issue continued. Tried out older kernels (6.11.0-28, 6.11.0-17, 6.8.0-57 I think), same issue.
I have an AMD GPU, Radeon RX 540 2GB. No amdgpu-pro, just default settings. Before the update it worked fine.
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This happened to me too last night, after applying a bunch of updates in Discover, which then wanted to reboot. It came back to a black screen.
I managed (eventually) to get a text virtual terminal with ctrl-meta-alt-F5, log in as root and add this guy’s 10-wayland.conf to /etc/sddm/conf.d. Then reboot. The greeter came back after that.
Link would have been here but apparently I’m not allowed. To find it: google “SDDM itself in wayland issues”.
I assume something in last night’s set of updates has messed up SDDM in some way.
Good luck!
-John
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This was really useful, I also made the update last night and after restarting the computer I couldn’t pass the black screen. I accessed the terminal and I run startplasma-wayland. It opened my session normally, I was really scared I didn’t want to reinstall everything. How I found was following some errors related to what you said, so I checked with journalctl -b -u sddm and looked in google for the errors related to “Failed to read display number from pipe” and ended I found the post sddm-failed-to-read-display-number-from-pipe-desktop-doesnt-start-on-its-own-anymore/163843 in forum.manjaro.org