There is a new bool property named Expect100Continue.
The default value is true. In your case, you'll want to set it equal to false:
The reason this new property exists is as follows:
- Virtually all web server will return the "100 continue" intermediate response when an "Expect: 100-continue" is sent in the request. (The Expect100Continue property controls whether the Expect header is added.
- By adding the "Expect: 100-continue" header, it allows a web server to reject the HTTP request before receiving the file data. For example, imagine you are trying to upload a 100MB file and it will fail because of some sort of permissions problem. It's better to get the failure immediately after sending the HTTP request header, rather than after the entire upload has been sent.
Mar 09 '14 at 10:33