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On KDE Wayland, screen sharing is a permission-controlled chain rather than a direct read of the display. The application asks org.freedesktop.portal.ScreenCast for a monitor or window, the XDG Desktop Portal and KDE backend show an approval dialog, and PipeWire carries the selected video stream. Remote keyboard, pointer, touchscreen, and clipboard access use additional portal permissions. A black stream, empty picker, missing Share button, or refused input usually means one link in that chain is missing or incompatible—not that changing a random graphics setting will help.
Work through the stack in order: identify the session and versions, test whether the problem affects one application or every application, verify the user-session portal and PipeWire services, approve the requested source and input devices, then troubleshoot KRFB/KRDC protocol, network, firewall, and credentials. The procedure below also explains why unattended headless access remains limited on Plasma Wayland.
How KDE Wayland screen sharing works
Wayland deliberately prevents ordinary applications from reading the entire desktop or injecting input without authorization. Instead, a compatible application requests a portal session.
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- ScreenCast portal: the application requests
org.freedesktop.portal.ScreenCast. The desktop presents a chooser for monitors or individual windows and asks you to approve the capture. - PipeWire transport: after approval, the portal exposes the selected source through a PipeWire remote. The application consumes that stream rather than reading the compositor’s framebuffer directly.
- RemoteDesktop portal: keyboard, pointer, and touchscreen control are authorized separately. A remote session can combine RemoteDesktop with ScreenCast and, where supported, Clipboard.
- Application and sandbox: the browser, Electron client, recorder, or Flatpak must know how to call the portal and must have the permissions its packaging requires.
This separation improves privacy: you choose exactly what is captured and which input devices may be controlled. It also creates several boundaries where a failure can look identical to an application bug.
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Recognize the failure pattern before changing settings
| What you see | Most useful first suspicion | What to test |
|---|---|---|
| Black video after sharing starts | PipeWire stream, portal backend, compositor integration, or application capture support | Try another portal-aware application and inspect the user-session portal/PipeWire logs |
| Empty monitor/window picker | KDE portal backend or ScreenCast session creation | Check whether every application has the same empty list |
| No Share button or no permission dialog | Application does not support the portal path, is sandboxed without required access, or the portal service is unavailable | Test a native build and a second application |
UnknownMethod: No such interface “org.freedesktop.portal.ScreenCast” |
The portal service at /org/freedesktop/portal/desktop does not expose ScreenCast |
Verify xdg-desktop-portal, the KDE backend, and session startup environment |
| Remote desktop connects but cannot control anything | View-only mode or RemoteDesktop/server input permission | Disable View Only and approve keyboard/pointer/touch devices |
| KRDC cannot connect | Hostname, port, server state, firewall, VPN, credentials, proxy/gateway, or missing protocol plugin | Check the network path and the selected VNC, RDP, or SPICE plugin |
| Connection works only after someone is at the KDE machine | Interactive portal authorization or the known lack of headless RDP | Plan for an already-authorized service, an X11 session, or another remote-access architecture |
1. Record the session and component versions
Do this before reinstalling packages. Plasma behavior changes across releases, and a portal problem can be caused by a mismatch between otherwise correctly installed components.
- At the login screen or in System Settings, confirm whether the session is Plasma (Wayland) or Plasma (X11). Do not assume that installing Wayland packages means the current login is using Wayland.
- Record the Plasma and KDE Frameworks versions.
- Record versions of
xdg-desktop-portal,xdg-desktop-portal-kde, PipeWire, WirePlumber, and the sharing application. - Record whether the application is a native package, Flatpak, Snap, browser tab, or Electron client. Sandboxed packaging changes portal permissions and runtime availability.
- Write down the monitor layout, whether you are on a local display or a VPN, and whether the failure is capture, control, clipboard, or connection.
Plasma 6 release notes document ongoing improvements to Wayland screen mirroring, clipboard sharing in the RDP server, and portal-based application permissions. Update Plasma, KDE components, PipeWire/WirePlumber, portals, and the application as a compatible group instead of relying on an old workaround from a different release.
2. Determine whether the application or the desktop stack is broken
Test a second portal-aware application
Use another current application that supports the ScreenCast portal. For example, test a browser-based meeting session against a separate browser, or test a recorder against a second recorder build. If the second application works, the desktop portal is probably functional; investigate the failing application’s portal implementation, sandbox permissions, or release-specific regression.
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Check native versus sandboxed packaging
A Flatpak or other sandbox may be unable to reach the expected portal runtime even though a native package works. Conversely, a native application may contain an older portal client. Compare the package types and versions, then test the same workflow in a known-compatible build. Do not grant broad filesystem or device access as a first response; screen capture and input should remain mediated by the desktop portal.
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3. Verify the portal, KDE backend, PipeWire, and WirePlumber
Confirm user-session services
The relevant processes normally run in the logged-in user session, not as arbitrary system daemons. Use your distribution’s service manager to inspect:
- the user-session
xdg-desktop-portalservice; - the KDE portal backend, commonly packaged as
xdg-desktop-portal-kde; - PipeWire;
- WirePlumber or the distribution’s PipeWire session manager.
Unit names differ by distribution and packaging, so treat the names above as search terms rather than universal commands. A typical diagnostic pattern is:
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systemctl --user status xdg-desktop-portal.service
systemctl --user status xdg-desktop-portal-kde.service
systemctl --user status pipewire.service
systemctl --user status wireplumber.service
journalctl --user -u xdg-desktop-portal.service -b
journalctl --user -u xdg-desktop-portal-kde.service -b
journalctl --user -u pipewire.service -b
journalctl --user -u wireplumber.service -bIf your distribution uses different unit names, search its package documentation or list active user units rather than copying these names unchanged. Look for failed starts, D-Bus activation errors, missing PipeWire remotes, or repeated crashes at the time you pressed Share.
Restart after package or session changes
After updating or reinstalling a portal, backend, PipeWire, or session manager, restart the affected user services using your distribution’s supported method. If the desktop still has the old environment, log out of Plasma and log back in; a reboot is useful when the display manager or session startup was changed. Restarting only the meeting application cannot repair a portal that was never activated.
Interpret the missing-interface error
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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/desktopThis means the D-Bus object exists but does not provide the ScreenCast interface the application requested. Check that the generic portal and KDE backend are installed, that the KDE backend is selected for the Plasma session, and that both were started after the current login. Reinstalling an unrelated GPU driver will not add a missing D-Bus interface.
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Check the PipeWire boundary
ScreenCast must both create a portal session and open a PipeWire remote. A dialog that appears followed by a black stream points to the hand-off after approval: PipeWire/WirePlumber state, compositor integration, or the application’s stream consumer. Review the user-session logs while reproducing the problem and check whether PipeWire reports a new stream or a permission failure.
4. Approve the correct source and input devices
Capture selection
When the portal dialog appears, select the intended monitor or window and explicitly approve the request. Sharing a single window is different from sharing a monitor: a minimized, hidden, or unsupported window may produce no usable frames even though monitor capture works. If the picker is empty, return to the portal diagnosis rather than repeatedly clicking Share.
Remote control selection
Viewing and controlling are separate operations. A remote client may receive video while keyboard, pointer, or touchscreen events remain denied because the RemoteDesktop request was not approved. Accept only the device classes the session needs.
Clipboard selection
Clipboard transfer is another capability, not an automatic consequence of video capture. The client and server must support it, the feature must be enabled, and a view-only connection may prevent useful input-side clipboard operations. Test with plain text first and avoid treating a failed file or rich-format transfer as proof that video sharing is broken.
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KDE’s native remote-desktop tools: KRFB and KRDC
KDE separates the server role from the client role:
| Tool | Role | Protocols and scope | Important distinction |
|---|---|---|---|
| KRFB | Server for the current Plasma desktop | VNC sharing of the session you configure | It publishes your desktop; it is not the program used to connect to another machine |
| KRDC | Client | VNC, RDP, and SPICE through protocol plugins | Plugin availability and restart state affect which connection types appear |
Sharing the current desktop with KRFB
- Open KRFB from the KDE application launcher on the machine whose desktop should be shared.
- Configure the VNC sharing settings, authentication, and whether remote users may view only or control the session. Use the narrowest permissions that meet the task.
- Confirm the server is actually running and note the address and listening port shown by the application or your distribution’s documentation.
- From the client, connect with a VNC-capable client. If the client sees the desktop but cannot interact, check both KRFB’s control permission and the client’s view-only setting.
Wayland’s portal authorization still matters for applications that capture or control the desktop through the session. A VNC server’s own permissions do not automatically grant every portal request.
Connecting with KRDC
- Open KRDC on the client machine and create a connection for the server’s protocol: VNC, RDP, or SPICE.
- Enter the correct host name or address and port, then supply the account, password, and domain information required by that server.
- Check that the matching KRDC protocol plugin is installed and enabled. KDE documents that changing plugin availability requires restarting KRDC before the new protocol is usable.
- For a local network, connect directly. For a remote network, account for VPN routing, a gateway, proxy, or an SSH tunnel exactly as the server administrator requires.
5. Troubleshoot KRDC connection failures by layer
Address and reachability
- Verify the host name resolves to the intended machine and that the port matches the server configuration.
- Confirm the server process is running and listening on that interface.
- Check local and remote firewall rules, security groups, and VPN routes.
- Try the same connection from a second client on the same network to distinguish KRDC from a server or network outage.
Authentication and gateways
- Re-enter the username, password, and domain exactly as the server expects.
- Check whether the server requires a proxy, gateway, or SSH tunnel and whether KRDC is configured for it.
- Do not paste passwords into bug reports or logs. KDE’s troubleshooting guidance asks for the KRDC version, protocol, local operating system, server software, and reproducible steps instead.
Protocol plugin and server compatibility
A missing VNC, RDP, or SPICE plugin can look like an invalid address. Confirm the protocol is offered in KRDC after restarting it, then verify that the server actually speaks that protocol. A successful TCP connection does not guarantee that authentication, graphics, input, or clipboard features match.
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Turn off View Only
In KRDC, disable View Only when you need keyboard or pointer control. A session can display perfectly while intentionally suppressing all input because this option is enabled.
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On the sharing machine, verify that the server allows control and that the requested input devices were approved through RemoteDesktop when applicable. If only one device class fails, test keyboard and pointer separately; that distinguishes a general authorization failure from a device-specific permission or client issue.
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Test clipboard independently
Enable Clipboard Sharing where the client and server expose that option, keep View Only disabled, and test a short plain-text value. Clipboard support can be limited by protocol, server version, client packaging, or content type even when video and pointer input work.
7. Account for Plasma and component release compatibility
Do not combine a new Plasma compositor with an old portal backend or an old application and assume the interfaces are interchangeable. Plasma 6 release notes describe improvements to Wayland screen mirroring, RDP-server clipboard sharing, and portal-based permissions, while behavior in older releases may differ.
- Update Plasma and KDE Frameworks through your distribution’s supported channel.
- Update
xdg-desktop-portaland the KDE backend together. - Update PipeWire and WirePlumber together when your distribution ships them as a coordinated stack.
- Update the browser, Electron client, recorder, KRFB, or KRDC that actually fails.
- Log out and back in after the update so the new session environment and D-Bus activation state are loaded.
If an update introduces a regression, record the exact working and failing versions and reproduce with a second application before reverting broad parts of the desktop.
8. Understand the headless and unattended limitation
KDE’s Plasma/Wayland known-significant-issues page, updated 15 April 2026, lists “No headless RDP.” This is not merely a missing checkbox. The portal model expects an authorized desktop session and user approval for capture and, separately, input control. A machine that must accept a connection before anyone can approve a dialog may therefore fail by design.
For unattended administration, choose an architecture that provides an already-authorized service, use a supported X11 session where its security model fits your needs, or deploy a different remote-access design intended for headless operation. Each option changes the security boundary: pre-authorized services and unattended access can expose the entire desktop or input devices without a person present, so restrict network reachability, authenticate strongly, and enable only the capabilities required.
Choose the right fix for your actual requirement
| Requirement | Capture scope | Control | Authorization model | Likely path |
|---|---|---|---|---|
| Join a meeting and present one application | Window | Usually none | Interactive ScreenCast approval | Portal-aware application plus working KDE portal and PipeWire |
| Present all monitors | Monitor or full desktop | Usually none | Interactive ScreenCast approval | Select the monitor in the portal chooser; diagnose empty lists at the portal boundary |
| Help a user interactively | Monitor or window | Keyboard/pointer, optionally touch | ScreenCast plus RemoteDesktop approval | Approve both capture and input; disable View Only in the client |
| Connect to a running Plasma desktop over VNC | Current desktop | Server-configured | KRFB authentication and permissions | Run KRFB, permit the required control level, and connect with a VNC client |
| Connect using RDP or SPICE | Server-defined | Server/client-defined | Protocol authentication plus server policy | Use KRDC with the matching plugin and restart after plugin changes |
| Start access before a user logs in or approves a prompt | Usually full desktop | Often required | Pre-authorized or headless service | Do not expect ordinary Plasma Wayland portals to provide this; evaluate X11 or another architecture |
What to include in a useful bug report
A concise report lets maintainers identify the failing boundary instead of asking for repeated guesses. Include:
- distribution and release;
- Plasma, KDE Frameworks, kernel, portal, KDE portal backend, PipeWire, WirePlumber, and application versions;
- Plasma Wayland or Plasma X11;
- native, Flatpak, Snap, browser, or Electron packaging;
- the exact symptom and the last successful step;
- whether a second application succeeds;
- the protocol, host/network path, and whether a VPN, proxy, gateway, or tunnel is involved;
- relevant user-session log lines around reproduction, with passwords, tokens, and private addresses removed.
The practical answer
For a black or missing share on KDE Wayland, begin with the portal boundary: verify that the application supports ScreenCast, that xdg-desktop-portal and the KDE backend expose org.freedesktop.portal.ScreenCast, and that PipeWire/WirePlumber are healthy in the logged-in user session. Then approve the intended source and any RemoteDesktop input devices. For KRFB or KRDC, treat VNC, RDP, and SPICE as separate protocol paths and check plugins, network reachability, credentials, firewall, and View Only independently. Finally, design unattended access around the documented headless limitation instead of expecting a package toggle to remove an interactive Wayland permission model.
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