Install libnotify3.0-cil by entering the following commands in the terminal:
sudo apt update sudo apt install libnotify3.0-cil
CLI library for desktop notifications
A library that sends desktop notifications to a notification daemon, as defined in the Desktop Notifications spec. These notifications can be used to inform the user about an event or display some form of information without getting in the user's way. . This package contains the notify-sharp library itself, built against Gtk# 3.0.