Multi-Version Cluster (MVC) is a new feature in R80.40.
MVC is a next generation upgrade method which replaces the deprecated "Connectivity-Upgrade" (CU).
For more information, see the Installation and Upgrade Guide for R80.40 and higher > Chapter "Upgrade of Security Gateways and Clusters" > Section "Upgrading ClusterXL, VSX Cluster, or VRRP Cluster" > Section "Multi-Version Cluster (MVC) Upgrade".
Important - The Multi-Version Cluster Upgrade is intended only to test the current configuration in the newer version. It is not intended for changing the Security Policy and installing it on cluster members with different software versions.
This solution has been verified for the specific scenario, described by the combination of Product, Version and Symptoms. It may not work in other scenarios.