If you have multiple vCenter Server instances configured in your environment, an attempt to add a new instance might fail because of conflicting unique IDs.
Problem
You try to add a vCenter Server instance to Horizon 7, but the unique ID of the new vCenter Server instance conflicts with an existing instance.
Cause
Two vCenter Server instances cannot use the same unique ID. By default, a vCenter Server unique ID is randomly generated, but you can edit it.