SUMMARY This has happened to me quite a few times now, and it is a pretty bad bug since it freezes my system. I am not 100 % confident that the system tray causes the issue, but it seems like it does. So what happens? Sometimes, when I hover/click on something in the systray, KDE starts horribly lagging and after a few seconds, freezes completely. The only thing moving and working is the mouse cursor. I have attached a system journal log which contains errors with timestamps approximately when KDE froze. Somehow, it recovered. STEPS TO REPRODUCE UNKNOWN OBSERVED RESULT KDE freezes completely. SOFTWARE/OS VERSIONS Linux/KDE Plasma: openSUSE Leap 15.2 (available in About System) KDE Plasma Version: 5.18.6 KDE Frameworks Version: 5.71.0 Qt Version: 5.12.7 ADDITIONAL INFORMATION System journal log: srp 18 19:07:48 krelnb plasmashell[3203]: file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:910: TypeError: Type error srp 18 19:07:50 krelnb plasmashell[3203]: qml: Warning: StackView: You cannot push/pop recursively! srp 18 19:07:50 krelnb plasmashell[3203]: __recursionGuard (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:791) push (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:568) replace (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:761) onActiveAppletChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/PlasmoidPopupsContainer.qml:49) expression for onExpandedChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/items/PlasmoidItem.qml:86) onVisibleChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/main.qml:379) srp 18 19:07:51 krelnb plasmashell[3203]: qml: Warning: StackView: You cannot push/pop recursively! srp 18 19:07:51 krelnb plasmashell[3203]: __recursionGuard (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:791) push (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:568) replace (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:761) onActiveAppletChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/PlasmoidPopupsContainer.qml:47) expression for onExpandedChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/items/PlasmoidItem.qml:74) onClicked (qrc:/plasma/plasmoids/org.kde.plasma.networkmanagement/contents/ui/CompactRepresentation.qml:31) srp 18 19:07:52 krelnb plasmashell[3203]: qml: Warning: StackView: You cannot push/pop recursively! srp 18 19:07:52 krelnb plasmashell[3203]: __recursionGuard (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:791) push (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:568) replace (file:///usr/lib64/qt5/qml/QtQuick/Controls/StackView.qml:761) onActiveAppletChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/PlasmoidPopupsContainer.qml:49) expression for onExpandedChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/items/PlasmoidItem.qml:86) onVisibleChanged (file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/main.qml:379)
UPDATE: the whole system tray is acting weird - when you click on an icon, a menu opens, but with nothing inside. This includes media menu, audio, network and all the other available ones.
It sounds like there's a serious issue with your KDE packages or how they're installed. What you're experiencing could not have been caused by a code error (or else we would have heard about it before from a million other people) and is most likely caused by a bad installation, a local misconfiguration, a locally-installed fork of the System Tray applet interfering with distro packager, a bad distro patch, or a graphics driver issue. I would advise you to contact the openSUSE developers for further assistance.