VCSA Upgrade - Fatal error during network preservation

Problem
Upgrading a vCSA 6.0 U3 to 6.5 U3 received in stage 2 at 50% of progress bar a "fatal error"

Error: Fatal error during network preservation

Solution
To solve the issue is enough to perform below steps and re initiate the upgrade process,

1. Login to https://<vCenterServer_FQDN>:5480 vami page
   
   
2. Navigate to Networking and enable IPV6 settings.
   
   
3. Select the NIC and IPv6 Settings and Select the below option:
   "Obtain IPv6 automatically through DHCP"
   
   

That's it