*** If you're not sure this is actually a bug or valid feature request, instead post about it at https://discuss.kde.org If you're reporting a crash, attach a backtrace with debug symbols; see https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports Please remove this comment after reading and before submitting - thanks! *** DESCRIPTION After upgrading KWin from 6.6.4 to 6.7.0, krfb-virtualmonitor crashes immediately with exit code 255. The issue is a Wayland protocol mismatch: KWin 6.7.0 sends event index 3 (serial) on the zkde_screencast_stream_unstable_v1 interface, but krfb's compiled-in protocol definition only knows events 0–2 (created, failed, closed), causing libwayland-client to abort. Error message (stderr): interface 'zkde_screencast_stream_unstable_v1' has no event 3 STEPS TO REPRODUCE 1. Run KWin 6.7.0 on a Wayland session (Plasma 6.7.0) 2. Run: krfb-virtualmonitor --resolution 1366x1024 --name "test" --password "test" --port 5901 3. Observe immediate crash with exit code 255 OBSERVED RESULT Process exits with code 255, no virtual output created EXPECTED RESULT Virtual output "test" appears in kscreen-doctor --outputs SOFTWARE/OS VERSIONS Operating System: Fedora Linux 44 kernel 7.0.12-201.fc44.x86_64, Wayland session KDE Plasma Version: 6.6.4 KDE Frameworks Version: 6.25.0 Qt Version: 6.10.2 Plasma version: 6.7.0 krfb 25.12.3 — crashes (same error) krfb 26.04.2 — crashes (same error) KWin 6.6.4-2 — both krfb versions work correctly ADDITIONAL INFORMATION Bisect: Confirmed regression between KWin 6.6.4 → 6.7.0. Downgrading KWin to 6.6.4-2 restores functionality immediately without any other changes.
Thanks for the crash report, and the troubleshooting, that's very helpful. As the message at the top of the summary says, if something crashed, we also need a backtrace of it so we can figure out what's going on. Can you please attach a backtrace of the crash, as detailed in https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports ? Thanks.
We are unable to provide a backtrace through normal means. When attempting to reproduce the crash under gdb, we encountered a separate issue caused by a partial package downgrade on our end (kwin 6.7.0 + kscreenlocker 6.6.4 version mismatch), which prevented kwin_wayland from starting at all. This was not a KWin bug — it was a consequence of our own recovery process. The SIGABRT source is identifiable from the error message itself: libwayland-client aborts when it receives event index 3 on zkde_screencast_stream_unstable_v1, which is not present in krfb's compiled-in protocol definition. Both krfb 25.12.3 and 26.04.2 are affected identically. We confirmed the regression bisect: KWin 6.6.4 works, KWin 6.7.0 breaks it. If you can confirm whether event 3 (serial) was added to zkde_screencast_stream_unstable_v1 in KWin 6.7.0, that would pinpoint the exact commit responsible
I'm not able to reproduce this with krdp and Plasma built from git-master The developers can look further into zkde_screencast_stream_unstable_v1. Thanks for the additional detail there, that's helpful.