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

System.Net.HttpWebRequest adds the header 'HTTP header "Expect: 100-Continue"' to every request unless you explicitly ask it not to by setting this static property to false:

System.Net.ServicePointManager.Expect100Continue = false;

Some servers choke on that header and send back the 417 error you're seeing.

Give that a shot.