iOS 9.3.2 HTTPS Server returning -1202 "The Certificate for this server is invalid"?

Question

I am requesting from iOS 9 device to https:// URL where iOS receiving error code -1202 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be “example.com” which could put your confidential information at risk." Which already mentioned on

https://developer.apple.com/library/content/technotes/tn2232/_index.html#//apple_ref/doc/uid/DTS40012884-CH1-SECGLOSSARY

FYI : The same request is working on iOS 10 & 11 devices with 200 Ok Response. Also i have already handled the challenge methods in my HTTP Class using NSURLSession API.

Here Server is using self signed certificate.