title: Catch exceptions in ASP.NET resulting from Generic Handler (ashx) file
body: <p>I am trying to get a different server side stack functioning with my ASP.NET site.  My ashx file seems to be throwing a 500 Internal Server Error.  How do I figure out what exception this ashx file is throwing or the reason the 500 is being thrown?  When I attach to my IIS 7 w3wp.exe process, it doesn't throw an exception, but I'm reading that this is likely the case.</p>
  
  <p>The ashx file lives in the root directory of my ASP.NET site, and the Properties have it set to compile.</p>
  
  <pre><code>GET http://uhc-8:8883/MyApp/ExtDirectProxy.ashx 500 (Internal Server Error) index.html:27
  Uncaught TypeError: Cannot read property 'isProvider' of null ext-all-debug.js:74832
  allow right click initializing for http://uhc-8:8883/MyApp/index.html rightclick.js:1
  allow right click processing http://uhc-8:8883/MyApp/index.html rightclick.js:25
  </code></pre>