vCenter Upgrade
Build Numbers for vCenter appliance
Check vCenter appliance build so you can re-create if upgrade fails so badly that snapshot is not recoverable. You will need the same installer to be able to recover the backup you took as the backup is version dependant
Backup vCenter Appliance
Make sure you take a backup of the appliance before making any changes:
Go to the VAMI: https://<FQDN of vCenter appliance>:5480 then select the backup tab at the bottom and backup to an SFTP server or other option