Cannot Enable Multiple NSX-T on Single vCenter Server

If an old NSX-T extension exists in vCenter Server, you cannot enable multiple NSX-T on the vCenter Server as NSX-T is already registered.

Problem

Old extension still exists in vCenter Server.

Cause

You registered NSX-T without enabling Multi NSX in vCenter Server and deleted NSX Manager without unregistering the vCenter Server.

Solution

1. Log in to https://<vCenter-Server-IP>/mob/?mob=ExtensionManager.
2. On the ExtensionManager page, go to method "unregisterExtension".
3. Add old extension "come.vmware.nsx.management.nsxt" and click Invoke method.