KDE Plasma freezes after entering password on NixOS 24.11

[vaibhavsagar]

Describe the bug

After upgrading to NixOS 24.11, I can't use the graphical login screen because it freezes after I enter my password. When I open a new virtual console using Ctrl+Alt+F1, I am able to successfully log in and then run startplasma-wayland, which launches the desktop and a KDE Wallet window asking me to enter my password (which is the same as my system password). I think this KDE Wallet behaviour is what is causing the graphical login freeze.

Steps To Reproduce

Steps to reproduce the behavior:

1. Launch a NixOS desktop using KDE Plasma
2. Attempt to log in
3. Observe freeze

Expected behavior

I expect to be able to log in using the graphical login screen

Screenshots

Additional context

Metadata

• system: "x86_64-linux"
• host os: Linux 6.6.63, NixOS, 24.11 (Vicuna), 24.11.709933.c71ad5c34d51
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.24.10
• channels(root): "nixos-24.11"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

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[geraldwuhoo]

I am seeing the same behavior with sddm on plasma5 with Xorg.

[reedriley]

I think I'm seeing this as well, on nixos-unstable (ac35b10). sddm + plasma6 + wayland.

[LoipesMas]

I also have this issue.

I think this KDE Wallet behaviour is what is causing the graphical login freeze.

I don't think that's the case. I tried removing the kwallet password (which disables the popup), as well as disabled the kwallet (in ~/.config/kwalletrc), none of it helped. And I also don't see any kwin processes during the freeze, so it seems like it freezes before even attempting to launch plasma? Or maybe plasma launches and immediately crashes or something and leaves sddm hanging.

I tried using lightdm (with GTK greeter) and it also doesn't work. After some time (or some clicking around?) it shows an error "Failed to start session" (or something similar) and lets you try again.
(Although I'm not sure if lightdm used to work with plasma, haven't tried it before)

[reedriley]

I'm no longer hitting this. I haven't updated anything - so either the issue I hit was spurious, it resolved itself, or rebuilding the font cache (which I did for a different issue) resolved it.

(In case it's the latter - I ran fc-cache -r because of the nerdfonts package split.)

[vaibhavsagar]

I tried using an empty password in the hope that it might resolve this issue for me, but I'm still getting the freezing after trying to log in, which indicates that this is probably not related to KDE Wallet after all.

[muggenhor]

I had the same problem. Then found this workaround #363797 (comment) and gave it a try:

services.displayManager.sddm.wayland.enable = true;

Plasma now starts up for me after hitting return/enter when the password is entered.

Without this option systemctl status display-manager.service listed two processes with X being one of them. Now it doesn't list X anymore. I guess something about X + SDDM is broken since 24.11?

[vaibhavsagar]

This worked for me, thank you!

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/plasma-6-login-screen-is-broken/57742/4