SUMMARY Every so often, when I click on the "New Notifications" icon in the system tray (and maybe other applets as well, it happens infrequently enough that I can't readily remember) the applet will launch but it will be invisible (i.e. completely transparent) and the panel (icons-only task-manager) will freeze. Everything else works properly, so I'm able to "fix" this by launching a terminal and doing killall plasmashell && kstart5 plasmashell. The following is from the systemd journal, but as I only remembered to check there after I'd already restarted the plasma shell, I can't be entirely sure that everything here was printed before the restart (but judging by the timestamps it's probably before, unless I somehow managed to restart the shell in the span of a mere 2 seconds): Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:424:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:259:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:259:13: QML ListView: possible QQuickItem::polish() loop Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:424:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:424:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:259:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:259:13: QML ListView: possible QQuickItem::polish() loop Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:424:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:424:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 05 13:43:03 ArchBox plasmashell[1226]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:259:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 05 13:43:05 ArchBox kwin_x11[1163]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 30769, resource id: 33554503, major code: 15 (QueryTree), minor code: 0 Jun 05 13:43:05 ArchBox kwin_x11[1163]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 30809, resource id: 33554446, major code: 15 (QueryTree), minor code: 0 Jun 05 13:43:05 ArchBox kwin_x11[1163]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 30848, resource id: 33554456, major code: 15 (QueryTree), minor code: 0 STEPS TO REPRODUCE 1. Receive a new notification. 2. Click on the "new notifications" icon in the system tray. 3. Based on how often I click on this icon to read the notifications, I'd say this is a rare bug that only happens like 1 in maybe 50 times or so. OBSERVED RESULT The plasma shell freezes. EXPECTED RESULT The plasma shell should not freeze. SOFTWARE/OS VERSIONS OS: Arch Linux KDE Plasma Version: 5.21.5 KDE Frameworks Version: 5.82.0 Qt Version: 5.15.2 + latest KDE patches ADDITIONAL INFORMATION Next time I encounter this bug I'll make sure to check if plasma components other than the panel still work or not (e.g. right-clicking on the Desktop to add a new widget) and also to check what has been printed in the systemd journal while the panel is still frozen, before I restart the plasma shell.
The last 3 lines in the provided journald snippet (the "QXcbConnection: XCB error: 3 (BadWindow)" ones) are unrelated after all, I checked and they're printed all over the place.
Cannot reproduce; AFAIK there were some performance improvements made here for Plasma 5.22. Since you're on Arch, can you check to see if it still happens in 5.22?
I've been running 5.22 since Wednesday and so far I haven't encountered this issue (usually it would happen at least once every two days if not once every day), so I guess we can close this report and if something changes I'll open a new one.
Just had it happen again. The output is exactly the same: Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: possible QQuickItem::polish() loop Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: possible QQuickItem::polish() loop Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:03 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: possible QQuickItem::polish() loop Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: possible QQuickItem::polish() loop Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ListView Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:416:29: QML ColumnLayout: possible QQuickItem::polish() loop Jun 15 21:56:17 ArchBox plasmashell[2141]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/FullRepresentation.qml:258:13: QML ListView: ListView called polish() inside updatePolish() of ColumnLayout This time it happened just after I launched Firefox and, while waiting for my previous session to load, I opted to check my notifications. And now that I think about it, I believe the previous times I had it happen were the same: launching Firefox (or maybe some other application that takes more than a couple seconds to fully load) and then checking the notifications to kill time. Could this be some obscure race condition?
It just so happens that when I reported last week about this bug showing its face again after the 5.22 release, I had just (i.e. a few hours before) installed KWinFT in order to see how it compares to KWin. After KWinFT crashed on me a couple of times (for unrelated reasons) I reverted back to KWin 5.22 proper, and as a side-effect I've been bug-free ever since. In other words, updating to Plasma 5.22 has seemingly fixed the issue, with only a brief regression period when I was using KWinFT and its associated libraries. So, I venture this could have something to do with KWin after all, even though it surfaces in the Plasma shell? Of course, I say "have to do" where at this point it's more like "had to do", so this is more of a rhetorical question. I again suggest to close this for the time being, and I'll report back if it ever happens again.
Dear Bug Submitter, This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging If you have already provided the requested information, please mark the bug as REPORTED so that the KDE team knows that the bug is ready to be confirmed. Thank you for helping us make KDE software even better for everyone!
*** Bug 414785 has been marked as a duplicate of this bug. ***
*** This bug has been marked as a duplicate of bug 414785 ***