title: 503 Error After Microsoft Request Routing Is Installed - 32 bit 64 bit madness
body: <p>I have a requirement to install the Microsoft Request Routing component for IIS 7.5 running on a Windows 2008 R2 SP1 64Bit machine.</p>
  
  <p>After installing Microsoft Request Routing via the Web Platform installer our ASP.NET 4.0 application gets a "HTTP Error 503. The service is unavailable."</p>
  
  <p>The Windows event log error details says:</p>
  
  <pre><code>The Module DLL 'C:\Program Files\IIS\Application Request Routing\requestRouter.dll' could not be loaded due to a configuration problem. The current configuration only supports loading images built for a AMD64 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see http://go.microsoft.com/fwlink/?LinkId=29349.
  </code></pre>
  
  <p>I can make this error go away by changing the application pool to run in 32 bit mode by changing the "Enable 32-Bit Applications" setting to true.</p>
  
  <p>However I would prefer not to have to do that to resolve the issue.</p>
  
  <p>My questions are:</p>
  
  <ol>
  <li>Why is the Microsoft Request Routing feature trying to load a 32 bit version, isn't there a 64 bit version for it?</li>
  <li>How do I resolve this issue without having to change my application pool to a 32 bit mode?</li>
  </ol>