Plasma can not be started

After installing Kubuntu 16.04 and restarting, I got the message "Plasma 5 caot be started". I tried recovery mode and at the end it was said "Plasma 5 caot be started because all shell packages are missing". I suppose that I can try to add them from a terminal, but what are these shell packages?

ASUS laptop Intel I7-6500, Nvidia Geforce 940, 8 GB RAM, dual boot Windows 10 and Kubuntu