Installer gives NetworkManager or avahi-daemon error

When Red Hat Enterprise Linux is installed with a graphical user interface (GUI), the Content Gateway installer recognizes systems running NetworkManager or avahi- daemon processes and emits an error similar to the following:

Error: The avahi-daemon service is enabled on this system and must be disabled before Content Gateway v8.5.x can be installed.
Please disable the avahi-daemon service with the following commands and restart the Content Gateway installation.
chkconfig --levels 2345 avahi-daemon off 
service avahi-daemon stop
Warning: Content Gateway is supported on Red Hat Enterprise Linux, Basic Server (no GUI) and is not supported on RHEL with a GUI.

To continue, the conflicting NetworkManager and avahi-daemon processes must be stopped.

  1. To disable the avahi-daemon service, enter the following commands:

    chkconfig --levels 2345 avahi-daemon off service avahi-daemon stop

  2. Restart the installer:

    ./wcg_install.sh