A friend of mine solved this issue and he said I could share it. It’s a quick solution that was tricky to find any documentation on resolving the issue. He had a vCenter upgrade that would not go past 50% on stage 2 of the upgrade. That’s the stage where the new vCenter is brought online and the data from the old vCenter is migrated to the new vCenter. Turned out to be a duplicate IP address between the old and new vCenters because the old vCenter wasn’t going down quick enough. Therefore, he went through the upgrade process again and disconnected the vNIC on the old vCenter when at 50% on stage 2. Then the upgrade successfully finished.