Error: "Daemon did not return Answer::Ping, as expected" when using systemd

[DaniD3v]

I'm using nixOS with the following self-written systemd service:

{pkgs, ...}: {
  systemd.user.services.swww = {
    Unit = {
      Description = "Wallpaper daemon";
      Documentation = ["man:swww-daemon(1)"];

      Requires = ["graphical-session.target"];
    };

    Service = {
      Type = "notify";
      ExecStart = "${pkgs.swww}/bin/swww-daemon";
    };
  
  Install.WantedBy = ["graphical-session.target"];
  };
}

Here's the systemd status:

● swww.service - Wallpaper daemon
     Loaded: loaded (/home/notyou/.config/systemd/user/swww.service; enabled; preset: enabled)
     Active: active (running) since Sat 2024-04-13 19:10:12 CEST; 4min 19s ago
       Docs: man:swww-daemon(1)
   Main PID: 42808 (swww-daemon)
      Tasks: 1 (limit: 18263)
     Memory: 312.0K
        CPU: 2ms
     CGroup: /user.slice/user-1000.slice/[e-mail]/app.slice/swww.service
             └─42808 /nix/store/0y86f4dihwy88fqbz9fdc8x50f8ixiyh-swww-0.8.1/bin/swww-daemon

Apr 13 19:10:12 nixOS systemd[2272]: Starting Wallpaper daemon...
Apr 13 19:10:12 nixOS swww-daemon[42808]: 17:10:12 [INFO] (main) Initialization succeeded! Starting main loop...
Apr 13 19:10:12 nixOS systemd[2272]: Started Wallpaper daemon.

(It's interesting that the date is 2 hours off but I assume that's not the main issue as that also happens when I run the daemon manually).

The time I start the service doesn't really matter. If I just put it in my hyprland.conf it works.
It also works when I start the daemon manually. Weirdly enough I get debug info when running it from the cli.

swww-daemon 
17:17:23 [INFO] (main) Initialization succeeded! Starting main loop...
17:17:23 [INFO] (main) Selected wl_shm format: Bgr888
17:17:23 [INFO] (transition) BumpPool with: 2 buffers. Size: 12150Kb

running 9.1 atm

swww -V
swww 0.9.1

[DaniD3v]

Sorry my bad I had 2 different versions. I installed unstable.swww in my home.packages and stable swww in the systemd service.

[Leonardo Gibrowski Faé]

It's fine. While developing swwwI made that error so many times I've started to consider ways to mitigating it... but haven't gotten around doing anything just yet.