Bug 425079

Summary: Some Plasma and Qt apps on X11 logs warnings in journal (qt.qpa.xcb)
Product: [Plasma] kwin Reporter: Aurélien Oudelet (auroud85_fr) <aoudelet>
Component: generalAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED WORKSFORME    
Severity: normal    
Priority: NOR    
Version First Reported In: 5.19.4   
Target Milestone: ---   
Platform: Mageia RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Aurélien Oudelet (auroud85_fr) 2020-08-06 18:34:00 UTC 
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.
Comment 1 Aurélien Oudelet (auroud85_fr) 2021-01-08 09:25:36 UTC 
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
Comment 2 Aurélien Oudelet (auroud85_fr) 2021-01-28 17:07:44 UTC 
With WORKAROUND in Comment 1