Investigate NSURLError `cannot parse error` for API calls

We have been seeing a NSURLError cannot parse error with error code -1017 for 0.01% of all the requests fired from our native app. We double checked the request headers and cookies but found no difference from the API calls that succeeded for the same path. For most of these requests, we found (through our analytics tools) that 99% of the times, there was no response received from the server(response object is nil); trying to understand why would a no response cause a cannot parse error. We do not get much information from error received as to what really went wrong, did the request even reach the server or was killed or modified by the OS? Any help or further detail will be very helpful.

Error in detail: Foundation.URLError(_nsError: Error Domain=NSURLErrorDomain Code=-1017 "cannot parse response" UserInfo={NSUnderlyingError=0x280eddc50 {Error Domain=kCFErrorDomainCFNetwork Code=-1017 "(null)" UserInfo={_kCFStreamErrorCodeKey=-1, _kCFStreamErrorDomainKey=4}}, NSErrorFailingURLStringKey=https://mydomain.com/path, NSErrorFailingURLKey=https://mydomain.com/path, _kCFStreamErrorDomainKey=4, _kCFStreamErrorCodeKey=-1, NSLocalizedDescription=cannot parse response})