Public bug reported:
Edubuntu 26.04 sets QT_QPA_PLATFORM=xcb globally in
/etc/profile.d/edubuntu-qt.sh.
On a standard Ubuntu 26.04 Wayland session this forces Qt applications
to use the X11/XCB backend instead of Wayland. This can prevent Flatpak
Qt applications from launching when they have Wayland and fallback-x11
permissions but no normal X11 socket access.
For example, the KWrite Flatpak (org.kde.kwrite) fails with:
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb"
The application launches correctly if the environment variable is
removed:
env -u QT_QPA_PLATFORM flatpak run org.kde.kwrite
My session reports:
XDG_SESSION_TYPE=wayland
WAYLAND_DISPLAY=wayland-0
QT_QPA_PLATFORM=xcb
The KWrite Flatpak permissions include:
sockets=wayland;fallback-x11;
I believe Edubuntu should avoid setting QT_QPA_PLATFORM=xcb globally and
allow Qt to select the appropriate platform backend automatically.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: edubuntu-artwork 26.04.11
ProcVersionSignature: Ubuntu 7.0.0-29.29-generic 7.0.12
Uname: Linux 7.0.0-29-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 17 00:16:36 2026
InstallationDate: Installed on 2026-05-19 (89 days ago)
InstallationMedia: Edubuntu 26.04 "Resolute Raccoon" - Release amd64
(20260423.1)
PackageArchitecture: all
SourcePackage: edubuntu-artwork
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: edubuntu-artwork (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2163613
Title:
QT_QPA_PLATFORM=xcb prevents Qt Flatpak apps launching on Wayland
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