Enable KDE Plasma Wayland Session on KDE Neon

Desired outcome

Log in to a KDE Plasma Wayland session instead of the default X11 session on a KDE Neon installation, gaining improved touchscreen support and smoother compositing.

Prerequisites

• KDE Neon User Edition installed and fully updated via Discover or sudo apt update && sudo apt full-upgrade.
• A graphics driver that supports Wayland:
  • Intel integrated graphics (default driver).
  • AMD GPU using the open‑source amdgpu driver.
  • NVIDIA GPU using the proprietary driver version 470 or newer.
• Administrative (sudo) access for driver updates, if needed.
• Basic familiarity with the System Settings application and the SDDM greeter.

Focused procedure

1. Open System Settings
   • Launch System Settings from the application menu.
   • Navigate to Workspace → Startup and Shutdown → Desktop Session.
2. Select the Wayland session
   • In the Desktop Session dropdown, choose Plasma Wayland.
   • Click Apply and close System Settings.
3. Log out and choose the session at the greeter
   • From the Plasma menu, select Leave → Log Out.
   • At the SDDM greeter, click your username, then press the Session (usually a gear icon) and select Plasma Wayland.
   • Enter your password and log in.

Expected checks

After logging in, verify that you are indeed running a Wayland session:

1. Open a terminal (e.g., Konsole) and run:

   echo $XDG_SESSION_TYPE

   Expected output: wayland.

2. Confirm that the Wayland compositor is active:

   ps -e | grep kwin_wayland

   You should see a line similar to 1234 ? 00:00:02 kwin_wayland.

3. Optional: In System Settings → About → Platform, the displayed platform should read Wayland.

4. Test a Wayland‑compatible application (e.g., Dolphin file manager) for smooth scaling and, if you have a touchscreen, verify touch input works.

Recovery / rollback options

If the Wayland session fails to start (black screen, fallback to a terminal, or inability to log in), you can revert to the X11 session:

1. At the SDDM greeter, click the Session selector and choose Plasma (X11) instead of Wayland, then log in.
2. If you cannot reach the greeter, switch to a virtual console with Ctrl+Alt+F2, log in, and remove the KWin configuration that forces Wayland:

   rm ~/.config/kwinrc

   Then reboot with sudo reboot. The system will fall back to the default X11 session.

3. As a last resort, boot the kernel with the nomodeset parameter (add it to the GRUB line) to force a basic graphics fallback, then undo the change after you have restored the greeter.

Limitations and practical verification

• Some legacy applications or screen‑recording tools that rely on X11 extensions may not work correctly under Wayland. Test any critical workflows before making the switch permanent.
• NVIDIA users must ensure the proprietary driver is version 470 or newer; older drivers lack full Wayland support and may result in a black screen.
• Verification is limited to the checks described above; there is no automated test suite included in this guide.