Upgrading vCenter 8 to vCenter 9: Fixing a Stage 2 Precheck DNS Resolution Error
I was doing an in-place vCenter upgrade from vCenter 8 to vCenter 9 using the VCSA 9 ISO. Stage 1 (deploying the new appliance) completed fine, but Stage 2 prechecks failed with a generic “internal error” in the installer UI. In this post I’ll show how I troubleshooted and solved it.