Same here (Kubuntu 18.04.01) - after removing blocked print jobs in CUPS service UI (http://localhost:631/) plasmashell started. Here is my gdb backtrace from the crash before: cl@supertux:~$ gdb /usr/bin/plasmashell GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git Copyright (C) 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from /usr/bin/plasmashell...(no debugging symbols found)...done. (gdb) r Starting program: /usr/bin/plasmashell [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [New Thread 0x7fffe1caa700 (LWP 5836)] [New Thread 0x7fffdb713700 (LWP 5837)] [New Thread 0x7fffd9cce700 (LWP 5838)] org.kde.plasmaquick: Applet preload policy set to 1 [New Thread 0x7fffd3bb5700 (LWP 5839)] [New Thread 0x7fffd1b58700 (LWP 5840)] Warning: all files used by qml by the plasmoid should be in ui/. The file in the path "file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/code/LayoutManager.js" was expected at QUrl("file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/ui/LayoutManager.js") Warning: all files used by qml by the plasmoid should be in ui/. The file in the path "file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/code/FolderTools.js" was expected at QUrl("file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/ui/FolderTools.js") [New Thread 0x7fff3e1f6700 (LWP 5841)] trying to show an empty dialog trying to show an empty dialog org.kde.plasmaquick: New Applet "Application Launcher" with a weight of 100 Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString) Trying to use rootObject before initialization is completed, whilst using setInitializationDelayed. Forcing completion Both point size and pixel size set. Using pixel size. Both point size and pixel size set. Using pixel size. Both point size and pixel size set. Using pixel size. trying to show an empty dialog org.kde.plasmaquick: New Applet "Digital Clock" with a weight of 50 Warning: all files used by qml by the plasmoid should be in ui/. The file in the path "file:///usr/share/plasma/plasmoids/org.kde.panel/contents/code/LayoutManager.js" was expected at QUrl("file:///usr/share/plasma/plasmoids/org.kde.panel/contents/ui/LayoutManager.js") trying to show an empty dialog org.kde.plasmaquick: Delayed preload of "Application Launcher" after 0 seconds KAStatsFavoritesModel::setFavorites is ignored KActivities: Database connection: "kactivities_db_resources_140737353652224_readonly" query_only: QVariant(qlonglong, 1) journal_mode: QVariant(QString, "wal") wal_autocheckpoint: QVariant(qlonglong, 100) synchronous: QVariant(qlonglong, 0) Entry is not valid "kontact.desktop" 0x55555863ca40 Entry is not valid "ktp-contactlist.desktop" 0x55555863ca40 Entry is not valid "kontact.desktop" 0x55555863ca40 Entry is not valid "ktp-contactlist.desktop" 0x55555863ca40 Closing SQL connection: "kactivities_db_resources_140737353652224_readonly" trying to show an empty dialog org.kde.plasmaquick: Applet "Application Launcher" loaded after 73 msec org.kde.plasmaquick: New Applet "Audio Volume" with a weight of 50 org.kde.plasmaquick: New Applet "Clipboard" with a weight of 50 org.kde.plasmaquick: New Applet "Device Notifier" with a weight of 50 org.kde.plasmaquick: New Applet "KDE Connect" with a weight of 50 Warning: all files used by qml by the plasmoid should be in ui/. The file in the path "file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/code/uiproperties.js" was expected at QUrl("file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/uiproperties.js") org.kde.plasmaquick: New Applet "Notifications" with a weight of 50 [New Thread 0x7fff27a04700 (LWP 5842)] libkcups: Create-Printer-Subscriptions last error: 0 successful-ok org.kde.plasmaquick: New Applet "Printers" with a weight of 50 libkcups: Get-Jobs last error: 0 successful-ok libkcups: Get-Jobs last error: 0 successful-ok org.kde.plasmaquick: New Applet "Updates" with a weight of 50 org.kde.plasmaquick: New Applet "Vaults" with a weight of 50 Plasma Shell startup completed libkcups: 4 Thread 1 "plasmashell" received signal SIGSEGV, Segmentation fault. 0x00007fff2a37d556 in JobModel::updateJob(int, KCupsJob const&) () from /usr/lib/x86_64-linux-gnu/libkcupslib.so (gdb) bt #0 0x00007fff2a37d556 in JobModel::updateJob(int, KCupsJob const&) () from /usr/lib/x86_64-linux-gnu/libkcupslib.so #1 0x00007fff2a381e9f in JobModel::getJobFinished() () from /usr/lib/x86_64-linux-gnu/libkcupslib.so #2 0x00007fff2a3863b5 in ?? () from /usr/lib/x86_64-linux-gnu/libkcupslib.so #3 0x00007ffff1e8f122 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #4 0x00007ffff2e6782c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #5 0x00007ffff2e6f0f4 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #6 0x00007ffff1e5f9a8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #7 0x00007ffff1e6211d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #8 0x00007ffff1eb92c3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #9 0x00007fffec0d9387 in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #10 0x00007fffec0d95c0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #11 0x00007fffec0d964c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #12 0x00007ffff1eb88ef in QEventDispatcherGlib::processEvents(QFlags) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #13 0x00007ffff1e5d9ea in QEventLoop::exec(QFlags) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #14 0x00007ffff1e66a84 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #15 0x0000555555572cfa in ?? () #16 0x00007ffff147cb97 in __libc_start_main (main=0x555555572320, argc=1, argv=0x7fffffffde88, init=, fini=, rtld_fini=, stack_end=0x7fffffffde78) at ../csu/libc-start.c:310 #17 0x000055555557309a in _start ()