Symptoms:
Note: Firstboot logs are located at /var/log/firstboot directory.
For more information on:
VMware vCenter Server Appliance 6.0.x
VMware vCenter Server Appliance 6.7.x
VMware vCenter Server Appliance 7.x
This issue occurs when the DNS record for the vCenter Server Appliance is incorrect or does not exist.
To resolve this issue, verify that the FQDN has a valid (internal) domain name system (DNS) registration before upgrading vCenter Server Appliance.
For more information about DNS requirements see: DNS Requirements for the vCenter Server Appliance and Platform Services Controller Appliance.