HTTP POST Returns Error: 417 “Expectation Failed.”

Question

When I try to POST to a URL it results in the following exception:

The remote server returned an error: (417) Expectation Failed.

Answer 1

In my situation, this error seems to occur only if my client's computer has a strict firewall policy, which prevents my program from communicating with the web service.

So only solution I could find is to catch the error and inform user about changing the firewall settings manually.