System.Net.WebException: The underlying connection was closed: The connection was closed unexpectedly

Question

I'm writing a .NET application which is supposed to post data to another .NET application. I use the following code to request the login page

WebProxy proxy = new WebProxy("http://proxy:80/", true);
HttpWebRequest webRequest = WebRequest.Create(LOGIN_URL) as HttpWebRequest;
//proxy.Credentials = new NetworkCredential("myusername", "mypassword", "domain"); 
// webRequest.Proxy = proxy;
webRequest.Proxy = WebRequest.DefaultWebProxy;

StreamReader responseReader = new StreamReader
                                  (webRequest.GetResponse().GetResponseStream());
string responseData = responseReader.ReadToEnd();

but it fails on this line

StreamReader responseReader = new StreamReader
                                  (webRequest.GetResponse().GetResponseStream());

with the error message :

System.Net.WebException: The underlying connection was closed: The connection was 
                         closed unexpectedly.

Answer 1

In my case, this solved the problem:

System.Net.ServicePointManager.Expect100Continue = false;

and none of the above.

Answer 2

Faced the same error for using http GET for an API that used https. Might be of help to someone.