Hi Smith, have you tried using Postman to hit the same REST webservice with the same payload to see if you actually get a response code?
Here is an example. The correct URL for REST webservice is http://dummy.restapiexample.com/api/v1/employee/156696 which will return 200 status code
If I temper the URL to :
http://dummy.restapiexample.com/api/v1/employee/156696X, in Postman it will still return code 200 but the response content will contain the error message from the webservice
In WFG, RESTAPIClENT will not receive the REST response code but instead it contains the execution error
And you get the execution exception error from the action history