title: Silverlight 4 OOB + Browser HTTP Stack + Client Certificates = FAIL?
body: <p>I'm having an issue where IIS 7.5 (on Windows 7 64-bit) is failing when I call it from an out-of-browser Silverlight 4 app using SSL and a client certificate, with the message "The I/O operation has been aborted because of either a thread exit or an application request. (0x800703e3)".  The request does make it to IIS. here is a sample from the failed request trace:  </p>
  
  <p><a href="http://www.slipjig.org/IISError.gif" rel="nofollow noreferrer">The I/O operation has been aborted because of either a thread exit or an application request. (0x800703e3) http://www.slipjig.org/IISError.gif</a></p>
  
  <p>I am using the browser HTTP stack, because the client HTTP stack does not support client certificates.  The client code attempting to hit the server is the Prism module loader.  If I run the app out-of-browser but ignore client certs, or if I run the application in-browser but require client certs, it works fine.  It seems to be the combination of the two that is causing the problem.</p>
  
  <p>I tried the following to gather more info:</p>
  
  <ul>
  <li>Used Fiddler to view the failing request.  It works if Fiddler is running (presumably because Fiddler is handling the client certificate differently?);</li>
  <li>Created an .aspx web form to serve up the module .xaps;</li>
  <li>Created an HTTPModule to see if I could intercept the request before it failed;</li>
  <li>Used a packet sniffer to see if I could tell if the client certificate was being sent correctly.</li>
  </ul>
  
  <p>None of the above gave me much useful information beyond what I could see in the trace file, although the Fiddler thing is interesting.</p>
  
  <p>Any ideas?  Thanks in advance!
  Mike </p>