The problem:
Applications will not launch from the KDE Application Launcher. They do launch from command-line and from Krunner.
The error (example is trying to launch kcalc):
Jul 23 09:16:12 systemd[1813]: Started apps-org.kde.kcalc-2b7d02e0cadf4a3bbc47c26f19014ccc.scope.
Jul 23 09:16:12 kwin_x11[25766]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 26591, resource id: 4194642, major code: 18 (ChangeProperty), minor code: 0
Jul 23 09:16:12 kcalc[31475]: qt.qpa.xcb: could not connect to display :0
Jul 23 09:16:12 kcalc[31475]: qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
Jul 23 09:16:12 kcalc[31475]: Failed to create wl_display (No such file or directory)
Jul 23 09:16:12 kcalc[31475]: qt.qpa.plugin: Could not load the Qt platform plugin "wayland" in "" even though it was found.
Jul 23 09:16:12 kcalc[31475]: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: wayland-org.kde.kwin.qpa, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
Jul 23 09:16:12 systemd[1813]: apps-org.kde.kcalc-2b7d02e0cadf4a3bbc47c26f19014ccc.scope: Succeeded.
Jul 23 09:16:12 kwin_x11[25766]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 26614, resource id: 4194643, major code: 18 (ChangeProperty), minor code: 0
My system:
- Operating System: openSUSE Tumbleweed 20200717
- KDE Plasma Version: 5.19.3
- KDE Frameworks Version: 5.72.0
- Qt Version: 5.15.0
- Kernel Version: 5.7.7-1-default
- OS Type: 64-bit
- Processors: 4 × Intel® Core™ i5-4590 CPU @ 3.30GHz
- Memory: 7.7 GiB of RAM
- Graphics Processor: GeForce GT 1030/PCIe/SSE2
- Graphics Driver: 4.6.0 NVIDIA 450.57 (latest from Nvidia)
- Running X11, not Wayland
Launching the same app from konsole is successful, no errors…it seems almost like the launch from the KDE Application Launcher is trying to use Wayland.