521662 2026-06-18 18:02:46 +0000 krfb-virtualmonitor crashes with "zkde_screencast_stream_unstable_v1 has no event 3" after upgrade to KWin 6.7.0 2026-08-02 05:37:35 +0000 1 1 2 Applications krfb krfb-virtualmonitor 26.04.2 Fedora RPMs Linux UNCONFIRMED regression NOR crash --- 0 freeusernamestuff grundleborg antti.savo kdedev 0 oldest_to_newest 2524310 0 freeusernamestuff 2026-06-18 18:02:46 +0000 *** 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. 2524362 1 kdedev 2026-06-18 19:56:13 +0000 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. 2524478 2 freeusernamestuff 2026-06-19 02:16:09 +0000 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 2526185 3 kdedev 2026-06-23 21:50:52 +0000 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.