title: What does an HTTP 500 error with a 121 sub-status signify?
body: <p>I have a Web Application running in Azure and I've had a few outages where the server is unresponsive. When I look in the IIS log, I see HTTP 500 errors with a <code>sc-substatus</code> of 121 and a <code>sc-win32-status</code> of 0.</p>
  
  <p>Omitting all other fields, the logs look like this, in this order:</p>
  
  <pre><code>sc-status sc-substatus sc-win32-status
  500 121 0
  </code></pre>
  
  <p>I can't find reference to a 500.121 error anywhere online.</p>