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Can't reach login screen after upgrading from 25.04, X not working

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    [SOLVED] Can't reach login screen after upgrading from 25.04, X not working

    Hello! I've been bashing my head for more than a couple of days now, so I thought to look for suggestions here. The other topics had different issues, so I'm opening a new one.
    Here's how it went: I've got a laptop with an AMD APU and a discrete AMD GPU as well. Upgrade procedure went fine, no errors. When I rebooted, I saw that tty1 was frozen on the kubuntu logo. I switched to tty2 to check if the system booted properly, and it did. I tried to start plasma manually, and I noticed that X11 wasn't installed anymore. A quick search online told me that it was normal, so I installed the x11 packages again thinking it would fix the issue, and it didn't. I was still unable to reach the login screen, so I thought that SDDM might have been missing too. After checking and reinstalling the usual culprits (plasma-desktop, kubuntu-desktop, sddm) still no login screen. I tried startplasma-wayland, and I was able to get back to the desktop. At that point it was clear that the issue was with the X server, so I tried startx to see what X was doing and... it wasn't working. It's log looks pretty normal, until the last row:

    [ 3286.056] (EE) Screen(s) found, but none have a usable configuration.
    [ 3286.056] (EE)
    Fatal server error:
    [ 3286.056] (EE) no screens found(EE)​

    Which is... weird. It shows all the resolution settings, and they all look fine. Reading through the X.org wiki, they should show issues in terms of identified specs to justify them not actually working. Still, I tried the solutions I found googling around the issue, nothing worked.The only way X manages to see the screens is when I pass nomodeset to the kernel. Trying to force amdgpu.modeset=1 isn't working either. I tried other parameters looking at the amdgpu wiki, nothing worked. Ultimately, It doesn't look like a graphic driver issue. I am able to launch plasma-wayland manually, graphic acceleration is working and I haven't noticed any issue after I start plasma. The logs don't show any error with the amdgpu driver either. Boot logs are also fine, at some point it just hangs there and waits to switch to the login screen, which never happens.
    I also tried to reinstall Xorg, but nothing again.
    I've also got a similar laptop that upgraded fine, and comparing the installed packages between the two doesn't show any discrepancy either. I'm really grasping at straws, anything else I can try?
    Edit: I've managed to get a workaround working. I've configured sddm to skip login and log automatically to the desktop using the wayland session. It saves me time switching to TTY2, logging in and starting plasma manually, but that's... not ideal I'm afraid.
    Thank you in advance!
    Last edited by Live; Nov 16, 2025, 06:13 PM.

    #2
    Originally posted by Live View Post
    ... so I installed the x11 packages again ...
    Did you install plasma-session-x11? That's the crucial one.
    Regards, John Little

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      #3
      Originally posted by jlittle View Post

      Did you install plasma-session-x11? That's the crucial one.
      Hello. Yes, that's the first package I reinstalled. If I pass nomodeset to the kernel, I'm able to correctly start an x11 session. It really looks like a graphic driver issue, but I can't pinpoint what's wrong, especially since amdgpu looks like it's working properly. SDDM/X don't like that though...

      Edit: Solved! I focused my searches on amdgpu +Xorg not working, and I finally found a working solution through this link. In case it goes down and somebody stumbles upon this topic in the future: I had to create a custom monitor.conf file in /usr/share/X11/xorg.conf.d/. I used the modeline for my screen taken from Xorg's log. Now Xorg actually manages to "see" my laptop display, so I can actually reach the login screen. It's not 100% perfect: now I'll try to see if I can add the second screen as well straight in the conf file. Still, it's working!
      Last edited by Live; Nov 17, 2025, 04:16 PM.

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