To ensure successful upgrade of the vCenter Server Appliance or Platform Services Controller appliance, you must preform some required tasks and pre-checks before running the upgrade.

Download and Mount the vCenter Server Appliance Installer.

Verify that the clocks of all machines on the vSphere network are synchronized. See Synchronizing Clocks on the vSphere Network.

Verify that your system meets the minimum software and hardware requirements. See System Requirements for the New vCenter Server Appliance and Platform Services Controller Appliance.

If you plan to deploy the new appliance on an ESXi host, verify that the target ESXi host is not in lockdown or maintenance mode.

If you plan to deploy the new appliance on an ESXi host, verify that the target ESXi host is not part of a fully automated DRS cluster.

If you plan to deploy the new appliance on a DRS cluster of the inventory of a vCenter Server instance, verify that the cluster contains at least one ESXi host that is not in lockdown or maintenance mode.

If you plan to deploy the new appliance on a DRS cluster of the inventory of a vCenter Server instance, verify that the cluster is not fully automated.

Verify that the appliance that you want to upgrade does not run on an ESXi host that is part of a fully automated DRS cluster.

Verify that port 22 is open on the appliance that you want to upgrade. The upgrade process establishes an inbound SSH connection to download the exported data from source appliance.

If you are upgrading a vCenter Server Appliance that is configured with Update Manager, run the Migration Assistant on the source Update Manager machine.

For GUI upgrade, you must run the Migration Assistant manually. See Download and Run VMware Migration Assistant on the Source Update Manager Machine.

For CLI upgrade, you can run the Migration assistant either manually or automatically. To run the Migration Assistant automatically, add the source.vum section section and run.migration.assistant subsection to your JSON template. See Upgrade Configuration Parameters.

Verify that port 443 is open on the source ESXi host on which the appliance that you want to upgrade resides. The upgrade process establishes an HTTPS connection to the source ESXi host to verify that the source appliance is ready for upgrade and to set up an SSH connection between the new and the existing appliance.

If you are upgrading version 5.5 of the vCenter Server Appliance and you have changed its host name, verify that the SSL certificate is configured correctly. For information about how to troubleshoot an error when you changed the vCenter Server Appliance 5.5 host name, see vSphere Troubleshooting in the VMware vSphere 5.5 Documentation.

Verify that you have sufficient free disk space on the appliance that you want to upgrade so that you can accommodate the data for the upgrade.

Create a snapshot of the appliance that you want to upgrade as a precaution in case of failure during the upgrade process.

If you use an external database, determine the database size and the minimum storage size for the new appliance. See Determine the Oracle Database Size and the Storage Size for the New Appliance.

If you use an external database, back up the vCenter Server Appliance database.

Verify that the new appliance can connect to the source ESXi host or vCenter Server instance on which resides the appliance that you want to upgrade.

If you plan to assign a static IP address and an FQDN as a system name in the temporary network settings of the appliance, verify that you have configured the forward and reverse DNS records for the IP address.

If you plan to assign a DHCP IP address in the temporary network settings of the new appliance, verify that the ESXi host on which you want to deploy the new appliance is in the same network as the ESXi host on which the existing vCenter Server Appliance runs.

If you plan to assign a DHCP IPv4 address in the temporary network settings of the new appliance, verify that the ESXi host on which you want to deploy the new appliance is connected to at least one network that is associated with a port group which accepts MAC address changes. Consider the default security policy of a distributed virtual switch, which is to reject MAC address changes. For information about how to configure the security policy for a switch or port group, see vSphere Networking.