[MonoTouch] 100% NullReferenceException in HttpWebRequest.GetRequestStream()

[Robert Jordan]

Hi Will,

On 09.10.2011 21:40, Will Stones wrote:
> Since upgrading to MonoTouch 4.2.2 and MonoDevelop 2.8 I'm experience a 100%
> NullReferenceException when making a call to
> HttpWebRequest.GetRequestStream() when running on an iOS 3.1.3 device.  I've
> pasted the exception trace below.
>
> The code which reproduces the exception is as follows:
>      HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
>      request.UserAgent = "MyUserAgent";
>      request.Timeout = 15000;
>      request.KeepAlive = true;
>      request.Method = "POST";
>      string requestString = GetQueryString();
>      byte[] postBytes = Encoding.ASCII.GetBytes(requestString);
>      request.ContentLength = postBytes.Length;
>      request.ContentType = "application/x-www-form-urlencoded";
>      // Crashes on this line
>      request.GetRequestStream().Write(postBytes, 0, postBytes.Length);
>
>
> The code used to work fine until I upgraded MT and MD (I'm afraid I've lost
> the installers for the versions I was using so I can't tell you when the
> problem was introduced).
>
> This issue is pretty critical for me...!  Can anyone confirm how long a fix
> for an issue like this is likely to take?  If you'd like any more info on
> this please let me know.

This looks like a bug in MT 4.2 new feature: "iOS Proxy support: we now 
pick the system proxy settings and use those in .NET APIs.  The new 
CFProxy type can be used to get to all the details."

As a workaround, try to set request's Proxy property like this:

request.Proxy =  GlobalProxySelection.GetEmptyWebProxy();

Robert