Created attachment 69292 [details] log file First of all I do my apologise if my english isn't well. Black display with bug report windows: Shell del desktop di Plasma (kdeinit4), signal: Segmentation fault. Everything is out of order except alt-tab, ctrl-alt-canc and ctrl-esc. If I reboot, after login appear black display with bug report windows.
Removing the worldclock plasmoid possibly gets your system back to a working state. The easiest way to do that is to login at the console (Ctrl+Alt+F1) and to remove the worldclock plasmoid from the plasma configuration. If you don't feel like editing the file by hand, you can also rename it: cd ~/.kde/share/config mv -i plasma-desktop-appletsrc plasma-desktop-appletsrc.backup
Thanks for the report. The Plasma worldclock widget has been rewritten now in QML for Plasma5 (and lacking some of the old features still). The old code is no longer maintained, so closing this now. Please try the new widget and report any issues or features you would like to see (re-)implemented. See also https://frinring.wordpress.com/2016/08/04/wip-plasma-world-map-wallpaper-world-clock-applet-powered-by-marble/