Authentication exception when using an NLB solution with Workflow Manager
When process system processes an order and the workflow manager installation is setup using a NLB solution you might receive this error.
Error: Microsoft.Workflow.Client.AuthenticationException: A response was returned that did not come from the Workflow Manager. Status code = 401
With Windows Server 2003 SP1 a loopback security check was introduced, and this is what is causing this error.
Check following links for solution.