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POProblem with webclient: Expectation failed?
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  1. POProblem with webclient: Expectation failed?
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    copied!<p>I have a custom Http Handler which manipulates HTTP POST and GET. I got the project working on a seperate isolated server now need to put it in production...</p> <pre><code>using (var client = new WebClient()) { client.Credentials = CredentialCache.DefaultCredentials; client.UploadFile("serverlocation:port", fileToUpload); } </code></pre> <hr> <p>For some reason now when using <code>client.UploadFile("", file);</code> i.e. forcing the HTTP POST</p> <pre><code>System.Net.WebException: The remote server returned an error: (417) Expectation failed. at System.Net.WebClient.UploadFile(Uri address, String method, String fileName) </code></pre> <p>What could this be? I know the code works, so what else? Maybe the server blocks HTTP POST requests?</p> <p>I have tried adding: </p> <p><code>ServicePointManager.Expect100Continue = false;</code></p> <p>But have had no success though i'm not 100% sure where this code should before, I assume before i'm using the WebClient</p> <hr> <p><strong>Edit 0 :</strong></p> <p>I have just <a href="http://social.msdn.microsoft.com/forums/en-US/netfxnetcom/thread/d5d85e6d-b870-4057-82c8-49bf849c98f5" rel="nofollow noreferrer">read</a> the following: </p> <p><em>Because of the presence of older implementations, the protocol allows ambiguous situations in which a client may send "Expect: 100- continue" without receiving either a 417 (Expectation Failed) status or a 100 (Continue) status. Therefore, when a client sends this header field to an origin server (possibly via a proxy) from which it has never seen a 100 (Continue) status, the client SHOULD NOT wait for an indefinite period before sending the request body.</em></p> <p>I believe this request is going through a proxy, which may have something to do with the issue.</p> <p><strong>Edit 1:</strong></p> <p>Believe this problem has to be with 100-continue because, using fiddler to see exactly what my application is sending with <code>WebClient.UploadFile</code> shows this:</p> <pre><code>POST http://XXX.XXX.XXX.XXX:8091/file.myhandledextension HTTP/1.1 Content-Type: multipart/form-data; boundary=---------------------8ccd1eb03f78bc2 Host: XXX.XXX.XXX.XXX:8091 Content-Length: 4492 Expect: 100-continue </code></pre> <p>Despite having put that line: <code>ServicePointManager.Expect100Continue = false;</code> before the using statement. I don't think this line actually works.</p>
 

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