SUMMARY Lots of apps from Plasma and kwin_x11 display lot of warning level error in journal like this: qt.qpa.xcb: QXcbConnection: XCB error: 8 (BadMatch), sequence: 20456, resource id: 54526467, major code: 130 (Unknown), minor code: 3 Current versions on Cauldron (Kmail and Dolphin 20.04.3, kwin_X11 5.19.4,...) This issue was previously reported against an error 9: https://bugs.kde.org/show_bug.cgi?id=366421 today is error 8... and: https://bugreports.qt.io/browse/QTBUG-55167 where a fix is provided but seems to not function. Steps to Reproduce: 1. Simply move mouse cursor on these apps (on menu, on icons,...) 2. See logs (Konsole, journalctl -f) OBSERVED RESULT Simply moving mouse cursor on interface like menu, icons, plasmmoids. Lots of warning level logs from kwin_X11, Kmail 20.04.3, Dolphin 20.04.3. Some lags on interface when too much log output. EXPECTED RESULT No error at all as GUI seems to work some. Or no error but debug or notice. SOFTWARE/OS VERSIONS Operating System: Mageia 8 KDE Plasma Version: 5.19.4 KDE Frameworks Version: 5.72.0 Qt Version: 5.15.0 Kernel Version: 5.7.12-desktop-1.mga8 OS Type: 64-bit Processors: 4 × Intel® Core™ i5-6600K CPU @ 3.50GHz Memory: 15.6 Gio of RAM Graphics Processor: GeForce GTX 1660 Ti/PCIe/SSE2 Nvidia non free 450-series drivers.
Such logging errors can be silenced by adding a file like this in /etc/xdg/QtProject/qtlogging.ini [Rules] qt.qpa.xcb.warning=false qt.qml.connections.warning=false
With WORKAROUND in Comment 1