Hi, I also have this problem on and off. I have not yet been able to discern any pattern. Sometimes it seems that starting certain applications (like the Citrix ICA client, with an actual remote window open) brings it about; other times, it seems like the system rolls dice on boot, and on unlucky rolls I get the notification until I reboot (but I haven't verified this).
The following gets logged to .xsession-errors whenever the "window switcher installation is broken" notification is displayed: 2018-06-13 19:31:55.120698500 Currrent active notifications: QHash(("notification 4", "KDE Power Management SystemBattery Critical (5% Remaining)")) 2018-06-13 19:31:55.120740500 Guessing partOf as: 0 2018-06-13 19:31:55.120751500 New Notification: "" "The Window Switcher installation is broken, resources are missing.\nContact your distribution about this." 20000 & Part of: 0 2018-06-13 19:31:55.125681500 QXcbConnection: XCB error: 3 (BadWindow), sequence: 26941, resource id: 100663316, major code: 18 (ChangeProperty), minor code: 0 Possibly relevant package versions: ii kdeplasma-addons-data 4:5.12.5-1 all locale files for kdeplasma-addons ii kwin-addons 4:5.12.5-1 amd64 additional desktop and window switchers for KWin ii kwin-common 4:5.12.5-1 amd64 KDE window manager, common files ii kwin-data 4:5.12.5-1 all KDE window manager data files ii kwin-style-breeze 4:5.12.5-1 amd64 KWin Breeze Style ii kwin-x11 4:5.12.5-1 amd64 KDE window manager, X11 version ii libkf5plasma5:amd64 5.46.0-1 amd64 Plasma Runtime components ii libkf5plasmaquick5:amd64 5.46.0-1 amd64 Plasma Runtime components ii libkwin4-effect-builtins1 4:5.12.5-1 amd64 KDE window manager effect builtins library ii libkwineffects11 4:5.12.5-1 amd64 KDE window manager effects library ii libkwineffects1abi5 4:4.11.22-3 amd64 library used by effects for the KDE window manager ii libkwinglutils11 4:5.12.5-1 amd64 KDE window manager gl utils library ii libkwinglutils1abi2 4:4.11.22-3 amd64 library with OpenGL utilities for the KDE window manager ii libkwinxrenderutils11 4:5.12.5-1 amd64 KDE window manager render utils library ii libplasma-geolocation-interface4 4:4.11.22-3 amd64 library for the Plasma geolocation ii libplasma-geolocation-interface5 4:5.12.5-1 amd64 Plasma Workspace for KF5 library ii libplasma3 4:4.14.36-1 amd64 Plasma Library for the KDE Platform ii libplasmaclock4abi4 4:4.11.22-3 amd64 library for Plasma clocks ii libplasmagenericshell4 4:4.11.22-3 amd64 shared elements for all the plasma shells ii plasma-containments-addons 4:4.14.2-1 amd64 additional containment plugins for Plasma ii plasma-dataengines-addons 4:5.12.5-1 amd64 additional data engines for Plasma ii plasma-desktop 4:5.12.5-1 amd64 Tools and widgets for the desktop ii plasma-desktop-data 4:5.12.5-1 all Tools and widgets for the desktop data files ii plasma-framework 5.46.0-1 amd64 Plasma Runtime components ii plasma-integration 5.12.5-1 amd64 Qt Platform Theme integration plugins for KDE Plasma ii plasma-scriptengine-javascript 4:17.08.3-2 amd64 JavaScript script engine for Plasma ii plasma-wallpapers-addons 4:5.12.5-1 amd64 additional wallpaper plugins for Plasma 5 ii plasma-widget-adjustableclock 4.1.4-1 amd64 Plasma widget clock to show date and time ii plasma-widget-folderview 4:16.04.1-1 amd64 plasma widget showing the content of a folder ii plasma-workspace 4:5.12.5-1 amd64 Plasma Workspace for KF5 ii qml-module-org-kde-kwindowsystem:amd64 5.46.0-1 amd64 provides integration of QML and KDE frameworks - kwindowsystem I'd be happy to attach an strace to the relevant process, but I have no idea which process that is. On a hunch, I tried the plasmashell process; grepping for system calls that return errors, I see: [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5476] recvmsg(8<UNIX:[218606->221700]>, {msg_namelen=0}, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable) [pid 5476] recvmsg(8<UNIX:[218606->221700]>, {msg_namelen=0}, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] stat("/home/korn/.local/share/kservicetypes5", 0x7ffcd257eb40) = -1 ENOENT (No such file or directory) [pid 5402] stat("/usr/local/share/kservices5", 0x7ffcd257eb40) = -1 ENOENT (No such file or directory) [pid 5402] openat(AT_FDCWD, "/usr/local/share/kservices5", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 ENOENT (No such file or directory) [pid 5402] stat("/usr/local/share/kservicetypes5", 0x7ffcd257eb40) = -1 ENOENT (No such file or directory) [pid 5402] stat("/usr/local/share/mime", 0x7ffcd257eb40) = -1 ENOENT (No such file or directory) [pid 5402] openat(AT_FDCWD, "/usr/local/share/mime", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 ENOENT (No such file or directory) [pid 5402] recvmsg(3<UNIX:[220545->219836]>, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5476] <... recvmsg resumed> {msg_namelen=0}, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] stat("/home/korn/.local/share/plasma/desktoptheme/.customized1/opaque/icons/dialog.svgz", 0x7ffcd2577160) = -1 ENOENT (No such file or directory) [ dozens of similar lines, looking for dialog.svg(z) all over the filesystem, omitted for brevity ] [pid 5402] access("icons/dialog", F_OK) = -1 ENOENT (No such file or directory) [pid 5402] access("/usr/share/icons/oxygen/base/8x8/emblems/dialog-information.svg", F_OK) = -1 ENOENT (No such file or directory) [ ditto for dialog-information.svg(z) ] [pid 5402] access("/usr/share/icons/oxygen/48x48/actions/dialog-information.svgz", F_OK) = -1 ENOENT (No such file or directory) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... recvmsg resumed> {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5428] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) [pid 5402] <... futex resumed> ) = -1 EAGAIN (Resource temporarily unavailable) I'm not sure how useful this is, nor how to provide more useful troubleshooting information. FWIW, the only dialog.svg installed is /usr/share/pixmaps/pidgin/dialogs/scalable/dialog.svg, but I have several likely-looking instances of dialog-information.svg. Also, since the problem is intermittent, it's probably not due to an actual missing file. Since this notification seems to be genuinely useless and just annoying, maybe it could be silenced somehow? Andras -- I, for one, am a great fan of Roman numeral puns.