This error shows in that case when the API connection is not established. There are two reasons for this error. The reasons are given below.
1. If you have deactivated and activated the VMware addon module.
2. Deleted the existing vCenter/ESXi server from "Server Setup" in module
In this case when you will activate the module again or add the new server under "Server Setup". Then in DB, there will be a new incremental ID that will be created. So, that's why it happens.
Solution:
Go to Setup >> Product/Services >> Product/Services, edit the specific products which have a WGS VMware module. Go to the "Module Settings" tab and save the module configuration again.
