Azure function : "Authentication failed because the remote party has closed the transport stream."

I had written some Azure Functions to integrate with D365 CRM and spent many hours pulling my hair,

PROBLEM
I was getting the same "Authentication failed because the remote party has closed the transport stream." when posting to this azure function API
SOLUTION
After changing my client target framework version from 4.5.2 to 4.6 I was able to do away with the issue