title: Troubleshooting an IIS .NET website outage
body: <p>Last night one of the websites (.NET 4.0 forms) hosted on my Win 2008 R2 (IIS 7.5) Server started to time out throwing the following error for all connected users.</p>
  
  <pre><code>TYPE     System.Web.HttpException
  MESSAGE  Request timed out.
  DETAIL   System.Web.HttpException (0x80004005): Request timed out.
  </code></pre>
  
  <p>The outage was confined to just one website within IIS, the others continued to work fine.</p>
  
  <p>Unfortunately I was unable to identify why the website was timing out. Here are the steps I took:</p>
  
  <ul>
  <li><p>First thing I did was look at the task manager which revealed normal CPU and memory usage. Network activity was also moderate.</p></li>
  <li><p>I then opened IIS to look at the live connections under 'Worker Processes'. There were about 60 live connections, so it didn't look like anything DDoS related.</p></li>
  <li><p>Checked database connectivity (hosted on a separate server), all fine!</p></li>
  <li><p>I then reset the website on IIS. That didn't work</p></li>
  <li><p>I tried to then do a complete <code>iisreset</code>...still no luck :(</p></li>
  <li><p>In the end (and under some duress) the only thing I could think to do to resolve this was to restart the server.</p></li>
  </ul>
  
  <p>Restarting the server worked but I am nervous not knowing why this happened in the first place. Can anyone recommend any checks that I failed to carryout? Is there an official checklist for working through these sorts of IIS problems? I have reviewed the IIS logs but don't see anything unusual on the run up to the outage.</p>
  
  <p>Any pointers or links to useful resources to help me understand and mitigate against this in future will be much appreciated.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>The only time I logged into the server that day was to add an additional web handler component (for remote deploy) to IIS Web Deploy. I'm doubtful this caused the outage as the server worked for for 6 hours after.</p>