Public bug reported: After several days using the KDE Plasma desktop, I suddenly found that all of the windows had become unresponsive. I could still move the mouse, but clicking didn't do anything. I could no longer change the volume with the volume buttons. Also, the panel clock stopped ticking upward. Fortunately, I could still use the keyboard to access a tty.
I would estimate this occurred roughly monthly. I still cannot consistently reproduce, and I wasn't doing anything unusual these interruptions occurred, just switching windows or typing in a textbox. This normally works from a tty: DISPLAY=:0 xdpyinfo but during these episodes it would just hang. I believe this would also hang after running and switching back to the graphical window: DISPLAY=:0 qdbus org.kde.KWin /KWin supportInformation But I don't recall for sure. This also hung: DISPLAY=:0 kwin --replace and showed an error: qt.qpa.screen: QXcbConnection: Could not connect to display :0 Next tried this: DISPLAY=:0 kquitapp5 plasmashell && kstart5 plasmashell Got a different error after a timeout: "Quitting application plasmashell failed. Error reported was:\n\n org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bug security policy blocked the reply, the reply timeout expired, or the network connection was broken." In a later instance, I was able to revive the system like this: kill -USR1 $(pgrep kwin_x11) DISPLAY=:0 kwin --replace I found this sufficiently convincing that is was an issue with Kwin and not another component, so I thought I should report this bug. Backtraces and strace logs are attached, as is my ~/.config/kwinrc and the output of the "qdbus org.kde.KWin /KWin supportInformation" when it is in a responsive state. $ lsb_release -rd Description: Ubuntu 18.04.4 LTS Release: 18.04 Kernel Version: 5.3.0-61-generic ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: kwin-x11 4:5.12.9.1-0ubuntu0.1 ProcVersionSignature: Ubuntu 5.3.0-61.55~18.04.1-generic 5.3.18 Uname: Linux 5.3.0-61-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.15 Architecture: amd64 CurrentDesktop: KDE Date: Sat Jul 4 16:13:00 2020 InstallationDate: Installed on 2020-02-01 (154 days ago) InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210) SourcePackage: kwin UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: kwin (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug bionic ** Attachment added: "Output of qdbus org.kde.KWin /KWin supportInformation" https://bugs.launchpad.net/bugs/1886293/+attachment/5389751/+files/qdbus_good.txt -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to kwin in Ubuntu. https://bugs.launchpad.net/bugs/1886293 Title: Kwin hangs in KWin::WindowPixmap::create() / xcb_request_check To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kwin/+bug/1886293/+subscriptions -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs