Qdbus /usr/lib/qt6/bin/qdbus has encountered a fatal error and was closed

swh · March 30, 2026, 8:05am

Hello, don’t know what’s happening but since a few days I received this message

/usr/lib/qt6/bin/qdbus has encountered a fatal error and was closed.

I don’t notice any issues during normal operation, but I get this message right after startup

           PID: 2646 (qdbus)
           UID: 1000 (swh)
           GID: 1000 (swh)
        Signal: 11 (SEGV)
     Timestamp: Mon 2026-03-30 09:38:11 CEST (1min 25s ago)
  Command Line: /usr/lib/qt6/bin/qdbus org.kde.kglobalaccel /component/kwin org.kde.kglobalaccel.Component.shortcutNames
    Executable: /usr/lib/qt6/bin/qdbus
 Control Group: /user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service
          Unit: user@1000.service
     User Unit: plasma-plasmashell.service
         Slice: user-1000.slice
     Owner UID: 1000 (swh)
       Boot ID: 1dfedd4d8ef1401087021769fb078f0b
    Machine ID: 6001749eb9ce4cdeb3c1789e21e4c0eb
      Hostname: starship
       Storage: /var/lib/systemd/coredump/core.qdbus.1000.1dfedd4d8ef1401087021769fb078f0b.2646.1774856291000000.zst (present)
  Size on Disk: 196.4K
       Message: Process 2646 (qdbus) of user 1000 dumped core.
                
                Stack trace of thread 2646:
                #0  0x00007f442b2a74d1 n/a (libQt6Core.so.6 + 0xa74d1)
                #1  0x00007f442ba1a9eb n/a (libQt6DBus.so.6 + 0x5e9eb)
                #2  0x00007f442ac4fa61 n/a (libc.so.6 + 0x40a61)
                #3  0x00007f442ac4fb3e exit (libc.so.6 + 0x40b3e)
                #4  0x00007f442ac366c8 n/a (libc.so.6 + 0x276c8)
                #5  0x00007f442ac367f9 __libc_start_main (libc.so.6 + 0x277f9)
                #6  0x000055e640430745 n/a (/usr/lib/qt6/bin/qdbus + 0x6745)
                
                Stack trace of thread 2651:
                #0  0x00007f442acadf32 n/a (libc.so.6 + 0x9ef32)
                #1  0x00007f442aca239c n/a (libc.so.6 + 0x9339c)
                #2  0x00007f442aca23e4 n/a (libc.so.6 + 0x933e4)
                #3  0x00007f442ad1c2f6 ppoll (libc.so.6 + 0x10d2f6)
                #4  0x00007f442b108744 n/a (libglib-2.0.so.0 + 0x60744)
                #5  0x00007f442b108825 g_main_context_iteration (libglib-2.0.so.0 + 0x60825)
                #6  0x00007f442b672222 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x472222)
                #7  0x00007f442b3845d6 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x1845d6)
                #8  0x00007f442b49efa2 _ZN7QThread4execEv (libQt6Core.so.6 + 0x29efa2)
                #9  0x00007f442b9f350e n/a (libQt6DBus.so.6 + 0x3750e)
                #10 0x00007f442b54d483 n/a (libQt6Core.so.6 + 0x34d483)
                #11 0x00007f442aca597a n/a (libc.so.6 + 0x9697a)
                #12 0x00007f442ad292bc n/a (libc.so.6 + 0x11a2bc)
                ELF object binary architecture: AMD x86-64

Posted it on KDE Discuss

swh · March 31, 2026, 7:46am

@luisbocanegra gave me a detailed answer on KDEDiscuss.

Some widgets use qdbus.

One can see which widgets/wallpapers/scripts are calling qdbus with ripgrep:

rg -ig “*.{qml,sh,js,xml}” ‘qdbus’ $HOME/.local/share/{kwin,plasma} /usr/share/{kwin,plasma}

In my case, the widget that is causing the problems should be ApplicationTitleBar

─❯  rg -ig "*.{qml,sh,js,xml}" 'qdbus' $HOME/.local/share/{kwin,plasma} /usr/share/{kwin,plasma}
rg: /home/swh/.local/share/kwin: No such file or directory (os error 2)
/home/swh/.local/share/plasma/look-and-feel/swhgitpurple/contents/layouts/org.kde.plasma.desktop-layout.js
388:                            "knownApps": "org.kde.accessibilityinspector.desktop,org.kde.kaddressbook.desktop,org.kde.akonadiconsole.desktop,org.kde.akregator.desktop,org.kde.alligator.desktop,org.kde.amarok.desktop,
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/home/swh/.local/share/plasma/plasmoids/com.github.antroids.application-title-bar/contents/ui/KWinConfig.qml
17:    property string reconfigureCommand: qdbusCommandName !== "" ? qdbusCommandName + " org.kde.KWin /KWin reconfigure" : ""
18:    property string getAllKWinShortcutNamesCommand: qdbusCommandName !== "" ? qdbusCommandName + " org.kde.kglobalaccel /component/kwin org.kde.kglobalaccel.Component.shortcutNames" : ""
19:    property string invokeKWinShortcutCommand: qdbusCommandName !== "" ? qdbusCommandName + " org.kde.kglobalaccel /component/kwin org.kde.kglobalaccel.Component.invokeShortcut " : ""
25:    property string qdbusCommandName: "qdbus"
121:    function updateQdbusCommandName() {
122:        updateCommandName(["/usr/lib/qt6/bin/qdbus", "qdbus", "qdbus6", "qdbus-qt6"], function (commandName) {
123:            qdbusCommandName = commandName;
124:            qdbusCommandNameChanged();
210:        updateQdbusCommandName();
215:    onQdbusCommandNameChanged: function () {

/home/swh/.local/share/plasma/plasmoids/com.github.antroids.application-title-bar/contents/ui/config/ConfigBehavior.qml
69:            text: "QDbus command is missing in the system!"
71:            visible: kWinConfig.qdbusCommandName === ""

/usr/share/plasma/plasmoids/luisbocanegra.panel.colorizer/contents/ui/configGeneral.qml
279:                text: "qdbus6 " + dbusName + " /preset preset /path/to/preset/dir/"
287:                text: i18n("Preview and switch presets using fzf + qdbus6 + jq:")
291:                text: "find " + presetsBuiltinDir + " " + presetsDir + " -mindepth 1 -prune -type d | fzf --preview 'qdbus6 " + dbusName + " /preset preset {} && jq --color-output . {}/settings.json'"
303:                text: `qdbus6 ${root.dbusName} /preset property 'stockPanelSettings.visible {"enabled": true, "value": false}'`
311:                text: `qdbus6 ${root.dbusName} /preset property 'stockPanelSettings.visible {"enabled": true, "value": true}'`

1093i3511 · March 31, 2026, 9:59am

I’m having the very same issues, but didn’t looked into it up so far.

It’s definitely ApplicationTitleBar, which I’ve got also in use. Usually I only recieve that crash notification directly after boot. But opening the configuration panel of the widget also produces the crashes.

Otherwise the widget works just fine. It has been already reported via various channels, the the widgets github here, the qt-dbus6 package as well as Qt itself.

Guess I’ll simply wait instead of chasing it proactively as it is only an minor inconvenience.

Thanks for looking into it @swh!

swh · March 31, 2026, 12:10pm

It didn’t bother me either. it worked. At some point I wanted to know where the error message came from and what it means
As you said, there are various sources that deal with this. So either continue to use it or deactivate it and wait for an update. I’ll probably deactivate it and use the klassy window decoration again

You’re most welcome

swh · April 7, 2026, 3:22pm

I updated this week. Error message seems to have disappeared. Everything is fine again