I am getting this error on datapower  when calling the API error show in picture.

I don't know why i am getting this error and how can i handle it. Kindly give me any suggestion.

Hi Shah,
It would appear you have a network error which is leading to an incomplete payload.  When the parse policy is attempted against that payload, you get the parse error.  The network error "The Version field in HTTP header is missing" sounds like you are getting a response from some backend server that should have something like HTTP/1.1 200 OK followed by a carriage return/line feed and then all of your HTTP response headers, but somehow that HTTP/1.1 (or 2.0, whatever version is being provided) isn't being sent by the backend.  Then you get a timeout error which appears to have the payload only partially received which is why the parse failed 1310720 bytes into the payload. Can you get a packet capture to see what your backend server is returning?  If the target url is https don't forget to enable tls/ssl session keys on the packet capture.  This may be something you'll need to have your network folks look into.  There could be some clues in the packet capture that L2 support could also review if you open a PMR.
Best Regards,
Steve Linn