Rather non descriptive and annoying error when setting up a 1000v for the first time. You can also see the “HTTP/1.1 400 Bad Request” along with the error message.
Cause:
Incorrect port
Or
You are connecting to a ESX server and no the vCenter server.
Resolution:
Change the port in vCenter to port 80.
‘Administration -> vCenter Server Settings -> Ports’
Or
Point it to the correct vCenter server.