You can use the GUI installer to perform an interactive upgrade of a vCenter HA cluster 6.5 or 6.7 that uses an external Platform Services Controller instance to vCenter Server appliance 7.0. You must run the GUI upgrade from a Windows, Linux, or Macintosh computer that is in the same network as the appliance that you want to upgrade.

A vCenter HA cluster consists of three vCenter Server appliances that act as Active, Passive, and Witness nodes. The Active vCenter HA node is upgraded using a migration-based upgrade while preserving the existing configuration.