Follow the steps below to upgrade a GMS 18.3.1 or 18.3.2 server to 18.4.x:
Download the ISO for GMS 18.4, 18.4.1, or18.4.2 from your Micro Focus Customer Center.
In a terminal, mount the GMS ISO using the following command:
mount <path to the GMS ISO> /mnt
Browse to /mnt and run the install.sh.
Follow the prompts to upgrade GMS.