Noctalia-shell run with NixOS modules can not find running shell instance after an update of noctalia-shell

[savrielynck]

Description

When running noctalia-shell ipc call or noctalia-shell msg outputs on NixOS (using the NixOS module instead of home-manager), the command fails with the error:

No running instances for "/nix/store/8g6h0czs2d1vxl4xdd8pbra9b9lvqsfd-noctalia-shell-2026-01-13_0f1eaa7/share/noctalia-shell/shell.qml"

Dead instances are listed, but no active instance is found.

Steps to Reproduce

1. Install noctalia-shell via the NixOS module (not home-manager).
2. Attempt to run either:
   • noctalia-shell ipc call
   • noctalia-shell msg outputs
3. Observe the error message above.

• Note: running systemctl --user restart noctalia-shell.service fixes the problem since the latest instance is picked-up

Expected Behavior

The IPC calls should successfully communicate with a running instance of noctalia-shell, returning the expected output (e.g., list of outputs or successful IPC response).

Environment

• Distro: NixOS
• Compositor: Niri
• Noctalia-shell Version: 2026-01-13_0f1eaa7 (from the error path)
• Monitor resolution: 2560*1440@165

### Additional Context

• The issue occurs specifically when using the NixOS module, not home-manager.
• Dead instances are detected, but no active instance is found, suggesting a potential issue with instance management or path resolution in the NixOS module configuration.
• Noctalia-shell is running

● noctalia-shell.service - Noctalia Shell - Wayland desktop shell
     Loaded: loaded (/etc/systemd/user/noctalia-shell.service; enabled; preset: ignored)
     Active: active (running) since Tue 2026-01-13 10:12:20 EET; 2s ago
 Invocation: b5b8de6cb6db4759a2fbe9855921e35d
       Docs: https://docs.noctalia.dev/docs
   Main PID: 15681 (.quickshell-wra)
      Tasks: 41 (limit: 19082)
     Memory: 146.6M (peak: 146.6M)
        CPU: 2.260s
     CGroup: /user.slice/user-1000.slice/user@1000.service/app.slice/noctalia-shell.service
             ├─15681 /nix/store/glcg5sqxlcgckyihdl4482vvqfwk3938-quickshell-0.2.1/bin/quickshell -p /nix/store/8g6h0czs2d1vxl4xdd8pbra9b9lvqsfd-noctalia-shell-2026-01-13_0f1eaa7/share/noctalia-shell
             ├─15808 /etc/profiles/per-user/savrielynck/bin/sh -c "temp_dir=\$(mktemp -d) && GIT_TERMINAL_PROMPT=0 git clone --filter=blob:none --sparse --depth=1 --quiet 'https://github.com/noctalia-dev/noctalia-plugins' \"\$temp_dir\" 2>/dev/null && c>
             ├─15810 git clone --filter=blob:none --sparse --depth=1 --quiet https://github.com/noctalia-dev/noctalia-plugins /tmp/tmp.8TBh8HRCdx
             ├─15908 /nix/store/fryiyyhhilpqhx2wc4b6l5gnxc8w18rg-git-2.52.0/libexec/git-core/git -c fetch.negotiationAlgorithm=noop fetch origin --no-tags --no-write-fetch-head --recurse-submodules=no --filter=blob:none --stdin
             ├─15909 /nix/store/fryiyyhhilpqhx2wc4b6l5gnxc8w18rg-git-2.52.0/libexec/git-core/git remote-https origin https://github.com/noctalia-dev/noctalia-plugins
             └─15910 /nix/store/fryiyyhhilpqhx2wc4b6l5gnxc8w18rg-git-2.52.0/libexec/git-core/git-remote-https origin https://github.com/noctalia-dev/noctalia-plugins

janv. 13 10:12:21 thor noctalia-shell[15681]:   WARN: QWaylandGLContext: Failed to create the decorations EGLContext. Decorations will not be drawn.
janv. 13 10:12:21 thor noctalia-shell[15681]:   WARN: QWaylandGLContext: Failed to create the decorations EGLContext. Decorations will not be drawn.
janv. 13 10:12:21 thor noctalia-shell[15681]:   INFO qml: [20260113-101221]     ImageCache ImageMagick available
janv. 13 10:12:21 thor noctalia-shell[15681]:   WARN: QWaylandGLContext: Failed to create the decorations EGLContext. Decorations will not be drawn.
janv. 13 10:12:21 thor noctalia-shell[15681]:   WARN: QWaylandGLContext: Failed to create the decorations EGLContext. Decorations will not be drawn.
janv. 13 10:12:21 thor noctalia-shell[15681]:   WARN: QWaylandGLContext: Failed to create the decorations EGLContext. Decorations will not be drawn.
janv. 13 10:12:21 thor noctalia-shell[15681]:   INFO qml: [20260113-101221]    ColorScheme Applying color scheme: Noctalia (default)
janv. 13 10:12:21 thor noctalia-shell[15681]:   INFO qml: [20260113-101221] AppThemeServic Generating templates from predefined color scheme
janv. 13 10:12:21 thor noctalia-shell[15681]:   INFO qml: [20260113-101221]     SystemStat Found k10temp CPU thermal sensor at /sys/class/hwmon/hwmon1
janv. 13 10:12:21 thor noctalia-shell[15681]:   INFO qml: [20260113-101221]          Color Reloading colors from disk

The reason I'm using the NixOS module instead of the home-manager module is because I do not want to sync my settings or have them in code. I only have a few modifications to do and therefore I don't mind to do it manually on a new machine if necessary.

[bokicoder]

See: NixOS/nixpkgs#246611

[kevb1973]

I'm experiencing the same issue on NixOS unstable, but under different circumstances.

• Nixpkgs version of Niri (25.11) installed with programs.niri.enable = true; works as expected.
• Git version of Niri installed with nix profile install and started with UWSM (to add entry to SDDM) does not work. Noctalia starts fine, but seems mostly broken.. workspace indicator is missing, ipc calls not working. Same error message 'No running instances'.
• Git version of Mango installed as above, launched with UWSM and Noctalia works fine.

So in my case, it seems to be either the latest version of Niri or Niri/USWM combo that's causing the issue. I'll test starting Niri git from VT with/without USWM to see if I can narrow it down.

[kevb1973]

Ok, so I tested it from a VT to take SDDM out of the picture.

It seems that starting Niri with UWSM is causing the issue in my case. I tried both the nixpkgs version and the most recent git version and had the same issues. Niri already starts processes with systemd, so maybe there is a conflict there.

Let me know if there is any info I can provide to help figure it out.

Edit: I've been starting Noctalia-shell with a systemd user service. If I start it directly with noctalia-shell it works fine, so my systemd service is the issue.

[ItsLemmy]

closing this, as this is not a Noctalia issue.
If you need more help regarding your nixOS setup I recommend our Discord and the nixOS channel.