When performing a VMware vCenter Upgrade for example from version 7 to version 8, you use the upgrade tool, this essentially works in two stages. Stage 1 deploy a new vCenter appliance on a temporary IP address, then Stage 2 copy all the configuration and data from the old vCenter appliance and then take over (it then shuts down the old appliance).
An issue we came across was that during the Stage 1 installation, you need to specify the network from a drop-down menu, in our case this was blank.
The documentation provides the following guidance:
The networks displayed in the drop-down menu depend on the network settings of the target server. If you are deploying the appliance directly on an ESXi host, non-ephemeral distributed virtual port groups are unsupported and are not displayed in the drop-down menu.
What we’d done was to specify the ESXi host as the target for the new vCenter appliance rather than the existing vCenter (I know this is a bit counter intuitive), but what should happen is that the installer should be able to query vCenter to retrieve the list of the networks on the Distributed Switch, it can’t do this if you’ve specified the ESXi host rather than the vCenter as the target.
Specifying the vCenter (which you are trying to replace) as the target rather than the ESXi host its going onto resolved the issue and allowed the installer to work as expected.