During the upgrade of a vCenter Server Appliance that uses an external Update Manager, the Migration Assistant must be running on the source Update Manager machine. This procedure describes how to download and run the Migration Assistant manually before the upgrade.

The Migration Assistant facilitates the migration of the Update Manager server and database to the new upgraded vCenter Server Appliance. The Migration Assistant uses port 9123 by default. If port 9123 is used by another service on your Update Manager machine, the Migration Assistant automatically finds a different free port to use.

Alternatively, if you plan to upgrade the vCenter Server Appliance by using the CLI installer, you can add the source.vum section section and run.migration.assistant subsection to your JSON template. For information about the CLI upgrade configuration parameters, see Upgrade Configuration Parameters.



  1. From the vCenter Server Appliance installer package, copy the migration-assistant directory to the source Update Manager machine.
  2. From the migration-assistant directory, double-click VMware-Migration-Assistant.exe and the provide the vCenter Single Sign-On administrator password.
  3. Leave the Migration Assistant window open until the upgrade of the vCenter Server Appliance finishes.


When the pre-checks are finished and any errors are addressed, your source Update Manager system is ready for the upgrade.

Caution: Closing the Migration Assistant window causes the upgrade process to stop.