Screencasting not working

[Niroid1237]

Trying to screencast on niri, discord has a black screen.

when i run niri like this: dbus-run-session niri --session
screencast works

System Information

• niri version: niri 25.05.1 (8ba57fc)

• Distro: Arch Linux x86_64

• GPU: AMD Radeon RX 6750 GRE 12GB [Discrete]

• CPU: 11th Gen Intel(R) Core(TM) i5-11400F (12)

[xdavidel]

I've the same problem, but on Slack - screencasting crashes with the following:

[627984:0724/012726.957480:ERROR:screen_capture_portal_interface.cc(48)] Failed to request session: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface “org.freedesktop.portal.ScreenCast” on object at path /org/freedesktop/portal/desktop
[627984:0724/012726.957492:ERROR:base_capturer_pipewire.cc(81)] ScreenCastPortal failed: 3
zsh: segmentation fault (core dumped) slack

I'm using xdg-desktop-portal-gnome but screencasting does not work regardless...

I'm using nixos with:

programs.niri.enable = true;

[Brisingr05]

Please start niri using niri-session and try screencasting again.

[xdavidel]

Please start niri using niri-session and try screencasting again.

That's how I ran it...
I also tried dbus-run-session niri --session with no luck...

I would be happy to try other solutions / ways to debug since I really liked Niri.

[Brisingr05]

Please start niri using niri-session and try screencasting again.

That's how I ran it... I also tried dbus-run-session niri --session with no luck...

I would be happy to try other solutions / ways to debug since I really liked Niri.

After starting niri with niri-session, run the following command in a terminal and share its output:

systemctl --user status xdg-desktop-portal.service xdg-desktop-portal-gnome.service pipewire.service

It would also be useful if your NixOS config is available to view.

[xdavidel]

Looks like there are some errors:

● xdg-desktop-portal.service - Portal service
     Loaded: loaded (/etc/systemd/user/xdg-desktop-portal.service; linked-runtime; preset: ignored)
     Active: active (running) since Thu 2025-07-24 11:51:11 IDT; 56min ago
 Invocation: 8fdd8ac46a7f48c2a5568f2b6625db64
   Main PID: 880039 (.xdg-desktop-po)
      Tasks: 5 (limit: 37685)
     Memory: 3M (peak: 3.9M)
        CPU: 107ms
     CGroup: /user.slice/user-1000.slice/user@1000.service/session.slice/xdg-desktop-portal.service
             └─880039 /nix/store/r7zjzmqjs4yd7w7gv2q63fyn2r4zy13i-xdg-desktop-portal-1.20.3/libexec/xdg-desktop-portal

Jul 24 11:51:10 caty systemd[3057]: Starting Portal service...
Jul 24 11:51:11 caty systemd[3057]: Started Portal service.
Jul 24 12:46:28 caty .xdg-desktop-po[880039]: A backend call failed: Unknown method CreateSession or interface org.freedesktop.impl.portal.GlobalShortcuts.
Jul 24 12:46:28 caty .xdg-desktop-po[880039]: Failed to close session implementation: GDBus.Error:org.freedesktop.DBus.Error.UnknownObject: Unknown object '/org/freedesktop/portal/desktop/session/1_3479/chromium_global_shortcuts'.

○ xdg-desktop-portal-gnome.service - Portal service (GNOME implementation)
     Loaded: loaded (/etc/systemd/user/xdg-desktop-portal-gnome.service; linked-runtime; preset: ignored)
     Active: inactive (dead)

● pipewire.service - PipeWire Multimedia Service
     Loaded: loaded (/etc/systemd/user/pipewire.service; linked-runtime; preset: ignored)
    Drop-In: /nix/store/3n5jh7x354fw3hb8pnhqzyxzwvvhsynh-user-units/pipewire.service.d
             └─overrides.conf
     Active: active (running) since Mon 2025-07-21 15:45:40 IDT; 2 days ago
 Invocation: 0f1cb20a593346b6b0936fb254c70edc
TriggeredBy: ● pipewire.socket
   Main PID: 3522 (pipewire)
      Tasks: 3 (limit: 37685)
     Memory: 11.3M (peak: 17.6M, swap: 8K, swap peak: 772K)
        CPU: 36.230s
     CGroup: /user.slice/user-1000.slice/user@1000.service/session.slice/pipewire.service
             └─3522 /nix/store/ap3284zdwi033wsmc0wcp8ww2gf3bmha-pipewire-1.4.5/bin/pipewire

Jul 21 15:45:40 caty systemd[3057]: Started PipeWire Multimedia Service.
Jul 22 21:44:52 caty pipewire[3522]: pw.node: (bluez_output.08_C8_C2_92_B1_EC.1-106) running -> error (Received error event)
Jul 23 22:15:05 caty pipewire[3522]: mod.x11-bell: X11 I/O error handler called on display :0
Jul 23 22:15:05 caty pipewire[3522]: mod.x11-bell: X11 display (:0) has encountered a fatal I/O error

Also my configs are available at gitlab.
It's a bit complex but the relevant niri sections are:
nixos module
home manager / config.kdl

[Viruzaum]

@xdavidel sodiboo/niri-flake#1170 (comment) seems like the problem you have

[cornservant]

If changing the GDK_BACKEND environment variable solves this I might create a gnome account and report this, because people will keep running into this problem, especially those migrating from Hyprland. Also according to gtk3/gtk4 docs GDK_BACKEND can be a list. It's just libgxdp (whose repo is just a few months old) that doesn't expect a list.

[xdavidel]

@xdavidel sodiboo/niri-flake#1170 (comment) seems like the problem you have

For me it didn't solve the issue...

I think those issues are a bit different, since I'm able to use FileChooser (but maybe it's using the gtk portal for that)...

Anyway, I tried to run after changing my config to include:

  environment.sessionVariables = {
    GDK_BACKEND = "wayland";
  };

and even tested the portal using:

❯ strings /proc/`pidof xdg-desktop-portal-gnome`/environ | grep GDK_BACKEND
GDK_BACKEND=wayland

[xdavidel]

I'm leaning toward blaming pipewire.
Just tried OBS and there is no screencapture option when I use Niri - when in Hyprland there is.

[xdavidel]

I was able to solve the issue by manually specifying the portals!

Using the following configuration for nix:

{pkgs, ...}: {
  programs.niri.enable = true;

  environment.systemPackages = with pkgs.unstable; [
    xwayland-satellite
  ];

  xdg.portal = {
    config.niri = {
      default = ["gnome" "gtk"];
      "org.freedesktop.impl.portal.Access" = "gtk";
      "org.freedesktop.impl.portal.Notification" = "gtk";
      "org.freedesktop.impl.portal.Secret" = "gnome-keyring";
      "org.freedesktop.impl.portal.FileChooser" = "gtk";
      "org.freedesktop.impl.portal.ScreenCast" = "gnome";
      "org.freedesktop.portal.ScreenCast" = "gnome";
    };
    extraPortals = with pkgs; [
      xdg-desktop-portal-gtk
      xdg-desktop-portal-gnome
    ];
  };
}

P.S: Not sure if I both org.freedesktop.impl.portal.ScreenCast and org.freedesktop.portal.ScreenCast are required.
I might check that later...

[cornservant]

According to the xdp docs the org.freedesktop.portal.ScreenCast entry (without "impl") shouldn't do anything.

[xdavidel]

I'll probably have time to test it today.
If it consistant I'll make a PR to nixpks and post that here.

@Niroid1237 can you check for your setup if it works by manually changing the configuration?

[Brisingr05]

@xdavidel: It shouldn't be necessary to manually specify the portals. I actually tested your config (the caty host, specifically) in a VM a couple of days ago, but forgot to get back to you 😅. For whatever reason, the Home Manager module for Hyprland causes this issue. I removed bundles.hyprland.enable from here and rebuilt the system. After restarting niri, the GNOME portal started and screensharing worked.

This was actually the first thing I did, because I encountered another user facing the same issue a while back.

[xdavidel]

@xdavidel: It shouldn't be necessary to manually specify the portals. I actually tested your config (the caty host, specifically) in a VM a couple of days ago, but forgot to get back to you 😅. For whatever reason, the Home Manager module for Hyprland causes this issue. I removed bundles.hyprland.enable from here and rebuilt the system. After restarting niri, the GNOME portal started and screensharing worked.

This was actually the first thing I did, because I encountered another user facing the same issue a while back.

Most interesting...
I tested that myself just now and it works, and the "choose screencast source" window is different...
My guess is that somehow Hyprland portal is getting in the way or something...

Thanks for letting me know.