Hello @Pavibhau_3698
Can you see HTTP access log files that are output on that Web server?
Maybe you can inspect more detailed error messages and reason why HTTP 500 was occurred.
Also, If possible, could you show us a screenshot of the PAD Flow Designer's action parameter dialog to tell us how you're sending a request to the Web service? If you provide us screenshot of Postman, we are able to compare success patern and failure patern.
Thank you.