Install gconf-defaults-service by entering the following commands in the terminal:
sudo apt update sudo apt install gconf-defaults-service
Description:
GNOME configuration database system (system defaults service)
GConf is a configuration database system for storing application preferences. It supports default or mandatory settings set by the administrator, and changes to the database are instantly applied to all running applications. It is written for the GNOME desktop but doesn't require it. . This package contains the PolicyKit service that allows users to edit the system-wide defaults from a user session.
Homepage: http://projects.gnome.org/gconf/
Version: 3.2.6-4ubuntu1
Section: universe/libs