title: ASP.NET: WebResource.axd call 404 error: how to know which assembly/resource is missing or responsible?
body: <p>I get a <strong>404 HTTP status error</strong> (not found) on <strong>a specific WebResource.axd</strong> call inside an ASP.NET 3.5 (AJAX) web application. I guess the error is thrown because a specific referenced assembly is missing in the bin folder/GAC. But I don't know which, since the page which requests the resource is very complex (I'm using third-party controls and ASP.NET Ajax.)</p>
  
  <p>Is it possible to know from the encrypted "d" querystring parameter of the query, like:</p>
  
  <pre><code>.../WebResource.axd?d=...
  </code></pre>
  
  <p>which assembly should create the content and is possibly missing?</p>
  
  <p><strong>Note:</strong> There are other WebRequest.axd calls which execute with success.</p>