Install xserver-xorg-xmir by entering the following commands in the terminal:
sudo apt update sudo apt install xserver-xorg-xmir
Description:
Xmir X server (transitional package)
This is a transitional package to ease upgrades to xmir. It can be safely removed.
Homepage: https://www.x.org/
Version: 2:1.19.6-1ubuntu4
Section: universe/x11