Cannot Enable or Disable Multiple NSX on a Single VMware vCenter

If an old NSX extension exists in VMware vCenter, you cannot enable or disable multiple NSX on the VMware vCenter as NSX is already registered.

Problem

Old extension still exists in VMware vCenter.

Cause

You registered NSX without enabling or disabling Multi NSX in VMware vCenter and deleted NSX Manager without unregistering the VMware vCenter.

Solution

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