https://bugs.kde.org/show_bug.cgi?id=526504
Bug ID: 526504
Summary: Fonts KCM crashes on open under Wayland: X error
BadDrawable (X_GetImage) in
KFI::CFcEngine::Xft::toImage via PreviewImageProvider
Classification: Applications
Product: systemsettings
Version First unspecified
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
STEPS TO REPRODUCE
1. Log in to a Plasma Wayland session.
2. Open System Settings > Text & Fonts (or run: kcmshell6 kcm_fonts).
OBSERVED RESULT
The application crashes within about a second of the page loading, every time.
Console output:
qrc:/kcm/kcm_fonts/main.qml:33:5: Unable to assign [undefined] to bool
X Error of failed request: BadDrawable (invalid Pixmap or Window parameter)
Major opcode of failed request: 73 (X_GetImage)
Serial number of failed request: 44
QBasicTimer::stop: Failed. Possibly trying to stop from a different thread
QObject::~QObject: Timers cannot be stopped from another thread
The font preview image provider runs Xft rendering on XWayland in a worker
thread. XGetImage fails with BadDrawable, the default Xlib error handler exits
the process from that thread, and the main thread segfaults during teardown
while it is inside the GL scene graph renderer (SIGSEGV).
Relevant frames of the preview thread:
#18 KFI::CFcEngine::Xft::toImage(int, int) const (kcm_fonts.so)
#19 KFI::CFcEngine::draw(QString const&, unsigned, int, QColor const&, QColor
const&, int, QString const&) (kcm_fonts.so)
#20 PreviewImageProvider::requestImage(QString const&, QSize*, QSize const&)
(kcm_fonts.so)
The full backtrace is attached.
EXPECTED RESULT
The page opens and shows font previews, or at least does not crash when the X11
preview path fails.
WORKAROUND
Running without an X11 display avoids the crash:
env -u DISPLAY systemsettings kcm_fonts
ADDITIONAL INFORMATION
- The page used to work on this machine. Plasma, KWin, Qt and XWayland were
last updated on Sep 8-10, 2026. Mesa was updated to 26.2.3 on Sep 24, 2026, and
the first crash was on Sep 30, 2026. A Mesa/glamor regression may be the
trigger, but this is not confirmed.
- Reproduced on 2 out of 2 attempts from System Settings and 1 out of 1 attempt
with kcmshell6.
- Display: built-in eDP-1 panel at 2560x1600 with 1.5x scaling. XWayland
reports a 1707x1067 root window. kwinrc contains [Xwayland] Scale=1.5.
- Possibly related: bug 495947 (Font Management crashes with an X error, but
BadLength rather than BadDrawable).
SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 44 (KDE Plasma)
KDE Plasma Version: 6.7.5
KDE Frameworks Version: 6.30.0
Qt Version: 6.11.2
Kernel Version: 7.2.7-200.fc44.x86_64 (64-bit)
Graphics Platform: Wayland
XWayland: 24.1.13
Mesa: 26.2.3
libXft: 2.3.8, fontconfig: 2.17.0
Hardware: ASUS ROG Flow Z13, AMD Radeon 8060S (Strix Halo, radeonsi)
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