Install gnome-session by entering the following commands in the terminal:
sudo apt update sudo apt install gnome-session
Description:
GNOME Session Manager - GNOME 3 session
The GNOME Session Manager is in charge of starting the core components of the GNOME desktop, and applications that should be launched at login time. It also features a way to save and restore currently running applications. . This package contains the required components for the standard GNOME 3 session, based on the GNOME Shell. It can be started from a display manager such as GDM, and requires 3D acceleration to work properly.
Version: 3.28.1-0ubuntu2
Section: universe/gnome