Public bug reported:
Versions:
apparmor 5.0.2-0ubuntu1~26.04.1
transmission-qt 4.1.1+dfsg-1ubuntu1.1
transmission-gtk 4.1.1+dfsg-1ubuntu1.1
On Kubuntu 26.04 (Plasma 6, X11 session, nouveau driver), the AppArmor
profile /etc/apparmor.d/transmission (shipped by the apparmor package)
prevents both Transmission frontends from working:
- transmission-qt starts but never creates a main window. The process sits
idle in its event loop; Qt debug logging stops right after GLX
gl-integration initialization.
- transmission-gtk exits immediately after printing:
libEGL warning: DRI3 error: Could not get DRI3 device
libEGL warning: Ensure your X server supports DRI3 to get accelerated
rendering
libEGL warning: DRI3: Failed to initialize
DRI3 and hardware GL are working on the system (Xorg log shows glamor and
DRI3 initialized; glxinfo reports accelerated rendering).
Confirmation that the profile is the cause:
- A copy of the binary run from another path (cp /usr/bin/transmission-qt
/tmp/tq; /tmp/tq), and therefore unconfined, opens normally.
- After disabling the profile (symlink into /etc/apparmor.d/disable/ and
apparmor_parser -R), both transmission-qt and transmission-gtk work.
Denials logged under profile="transmission-qt" (count, path):
2 /home/<user>/.cache/transmission-qt/
17 /home/<user>/.config/kcminputrc
17 /home/<user>/.config/kdedefaults/kcminputrc
17 /proc/sys/kernel/core_pattern
1 /run/user/1000/iceauth_*
1 /sys/devices/system/node/
2 /usr/share/transmission/translations/transmission_en.qm
The profile appears not to cover paths used by the Qt frontend and KDE
Frameworks: the app's own translations, its cache directory (also used by
Qt for the shader cache), KDE input config, and the ICE session-management
auth file. The Qt hang is likely Qt/Mesa stalling on one of these denied
accesses during OpenGL setup.
Workaround: disable the profile.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: apparmor 5.0.2-0ubuntu1~26.04.1
ProcVersionSignature: Ubuntu 7.0.0-34.34-generic 7.0.14
Uname: Linux 7.0.0-34-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Thu Oct 1 00:04:02 2026
InstallationDate: Installed on 2024-10-01 (729 days ago)
InstallationMedia: Kubuntu 22.04.5 LTS "Jammy Jellyfish" - Release amd64
(20240911)
ProcKernelCmdline: BOOT_IMAGE=/boot/vmlinuz-7.0.0-34-generic
root=UUID=f318e2a4-79dc-49cc-9838-274e7b2f5b05 ro quiet splash
SourcePackage: apparmor
Syslog:
2026-09-30T23:34:41.515638-03:00 milson-Aspire-TC-705 dbus-daemon:
apparmor="DENIED" operation="dbus_method_call" bus="accessibility" path="/"
interface="org.freedesktop.DBus.Peer" member="Ping" name=":1.1" mask="receive"
pid=175700 label="transmission-qt" peer_pid=2670 peer_label="unconfined"
2026-09-30T23:35:11.517893-03:00 milson-Aspire-TC-705 dbus-daemon:
apparmor="DENIED" operation="dbus_method_call" bus="accessibility" path="/"
interface="org.freedesktop.DBus.Peer" member="Ping" name=":1.1" mask="receive"
pid=175700 label="transmission-qt" peer_pid=2670 peer_label="unconfined"
2026-09-30T23:41:43.570435-03:00 milson-Aspire-TC-705 dbus-daemon[176832]:
[session uid=120 pid=176832 pidfd=5] AppArmor D-Bus mediation is enabled
2026-09-30T23:41:51.924009-03:00 milson-Aspire-TC-705 dbus-daemon[177048]:
[session uid=1000 pid=177048 pidfd=5] AppArmor D-Bus mediation is enabled
UpgradeStatus: Upgraded to resolute on 2026-09-07 (23 days ago)
** Affects: apparmor (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute
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https://bugs.launchpad.net/bugs/2169100
Title:
transmission profile breaks transmission-qt and transmission-gtk on
Kubuntu 26.04 (KDE/Qt paths denied)
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