KDE Plasma got error in Ubuntu 18.04 LTS

So I installed sddm pack in my Ubuntu then change the login screen to KDE and desktop session to Plasma. When I login to my account i get KDE boot screen and when it stops the ring, I got the cursor and I got a message box said:

"All shell packages missing. Contact your distro"

Then I hit Enter, it closes the box and nothing happened. I got stuck in KDE boot screen with no dock, no menu bar, no icon, nothing, just KDE boot screen.

Specs:

• VAIO Z series (VGN-Z56GG-B)
• Intel Core 2 Duo P9700(2.8Ghz, i386)
• nVidia GeForce 9300 GS and Mobile 4 Intel Chipset
• OS: Ubuntu and Windows 8.1 dualboot

Please help!

You have to reinstall Kubuntu task package by

sudo apt-get install --reinstall kubuntu-desktop^

In the end of above line note ^ - it means task package, so all KDE packages will be installed as in normal Kubuntu system.

Then reboot.