• This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.
  • Verify the URL is correct and it is working. If working, confirm the WSDL is visible. 
  • Try to access the URL from a browser on your server to isolate variables. 
  • If using a Windows service to make the API call, verify that nothing changed with the account the service is using to access the internet.