Resolution: If the rest binding is missing the response code for the reply activity, then the application will throw an error/exception. You have to add the response status code that is configured inside the reply activity in a catch (e.g., 400, 500) to the REST binding. Otherwise the REST client will not be able to get the contents of the reply activity as the exception and the above exception will be thrown. Refer to the attached (Fileanme: status_code_configuration.png) for configuring the status code.