nixos/Plasma6 Screenshare Portal is not avalible on KDE for wayland (and other applications)

[SpiderUnderUrBed]

Nixpkgs version

• Unstable (25.05)

Describe the bug

Screenshare does not work for discord, whether it be on any browser, or client apps. This is because KDE given to me by nixos or wayland shipped lacks the interface/portal for screenshare (I found dbus screencast/share missing and interfaces missing), I imagine this would affect other applications as well. Although I have not tested it

https://discourse.nixos.org/t/how-to-fix-debug-discord-screenshare-issues-on-kde/63784/29
^ I discussed it on the forum, as well as tried to debug the issue, more on that for the logs (I recommend reading the thread)

Steps to reproduce

This is my best guess on how to reproduce the issue without trying my config:

1. Make a new nixos system, with plasma 6 on unstable, (i am on 6.3.5, and I updated recently), more precisely close to 25.05.20250510.d89fc19, or look at the metadata section
2. Open the KDE wayland session
3. try discord screenshare on any platform.
   If you cannot recreate it, maybe try my configuration, in a vm or on host, through I think it will be more effective if you simply look through it (its a tiny bit messy):
   https://github.com/SpiderUnderUrBed/nixos-files

Expected behaviour

Discord screenshare should work on kde plasma 6, (6.3), on wayland, and should allow me to share my screen or window

Screenshots

I have a video but I dont think it will provide any additional useful information (taken from phone)

Relevant log output

https://pastebin.com/Sf0gz6Y2
^ Starting xdg desktop portal manually (/nix/store/4mxb4j4ma1h88c5afhvny0jl48zfmkg6-xdg-desktop-portal-kde-6.3.5/libexec/xdg-desktop-portal-kd)
You see indications of the missing interface here:
`kde.plasma.wayland.client: Unknown interface announced:  zkde_screencast_unstable_v1 / 68 / 5`
https://pastebin.com/7jdw0Pjf
 ^ with librewolf when i try screenshare
Same result. No extra logs
^ with brave
Same log with vesktop
^ with vesktop
Same logs as everything else (this screen shares, but only a black screen)
^ Vencord and discord (kinda different from native, but not enough I dont think it has any unique issue)

If you do want the brave and librewolf logs:
https://pastebin.com/QfPyR3ze
^ brave
https://pastebin.com/byf6zB59
^ librewolf

Additional context

https://discourse.nixos.org/t/how-to-fix-debug-discord-screenshare-issues-on-kde/63784/29
^ as mentioned previously, I talked about this issue with lots of information in the forums

Also, as I mentioned earlier, this does not work on OBS, I found out as I tried to record discord failing with screen share

Plasma manager exists in my home-manager configuration, but i do not use it

I think this is a bug, as nothing in my system should conflict with kdes ability to share my screen

System metadata

• system: "x86_64-linux"
• host os: Linux 6.14.6-cachyos, NixOS, 25.05 (Warbler), 25.05.20250510.d89fc19
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.28.3
• nixpkgs: /nix/store/ccfwxygjrarahgfv5865x2f828sjr5h0-source

Notify maintainers

---

Note for maintainers: Please tag this issue in your pull request description. (i.e. Resolves #ISSUE.)

I assert that this issue is relevant for Nixpkgs

• I assert that this is a bug and not a support request.
• I assert that this is not a duplicate of an existing issue.
• I assert that I have read the NixOS Code of Conduct and agree to abide by it.

Is this issue important to you?

Add a 👍 reaction to issues you find important.

[dantefromhell]

[UPDATE] Config error on my end.

I'm seeing the same issue when trying to screenshare using Zoom, Brave or Vivaldi.

Starting vivaldi from the cli I can see the following log line:

[3579700:3579700:0520/014142.557629: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

Looking at the output of nix run nixpkgs#door-knocker the Screen Cast portal is not available.

Manually starting all xdg related services in ls -l /etc/systemd/user | grep -i xdg changes nothing.

FYI This issue might not only be affecting KDE, I've been unsuccessfully trying to debug this on niri for a while now.

[nixos-discourse]

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

https://discourse.nixos.org/t/how-to-fix-debug-discord-screenshare-issues-on-kde/63784/31

[SpiderUnderUrBed]

Someone managed to fix their issue because they were using environment.sessionVaribles with mkForce which broke xdg portals, that isn’t causing my problem because I do not use mkForce for my environment.sessionVaribles, I would MASSIVELY appreciate it if someone could look at my config and tell me what could potentially be the cause? I already tried alot of debugging and I am a bit lost:
https://github.com/SpiderUnderUrBed/nixos-files
https://github.com/SpiderUnderUrBed/home-manager

[Nick1296]

I am also suffering from the same problem on nixos-unstable, in my case tough, everything works correctly in 24.11 and by default I have both the kde and gtk portals running.

Using nixos-unstable instead on the xdg-desktop-portal is automatically started and it just outputs a very cryptic error: Realtime error: Could not get pidns: Could not fstatat ns/pid: Not a directory and neither the gtk or kde portal are started

[Nick1296]

I just found a workaround that might be relevant to to this issue:

In my case the screensharing problems was due to this bug in home manager.

And I ended up fixing it by adding this to my home-manager configuration.

I tested both discord and zoom on nixos-unstable and screensharing seems to be working properly, so hopefully this can help other people too!

[SpiderUnderUrBed]

@Nick1296 Your fix did work! Screenshare now works on my system. I will leave this issue open until xdg portals 1.20.3 is merged (updating 1.20.0), and a following PR is made that fixes this issue, as mentioned in the bug you linked, the issue where home manager overwrites the xdg portal directory where kde plasma would also put their portals, so a pr which will probably set a different xdg data dir for home-manager, or something similar.