title: Why are blank pages being served with "200 OK" for asp.net errors in IIS 8.5 (Win 2012 R2)?
body: <p>I've set up a new Windows 2012 R2 server running IIS 8.5.</p>
  
  <p>We noticed that when an error occurs (eg the ASP.NET State Service was not running) that instead of outputting a 500 status code error screen, the request actually returns a totally blank page (only headers - with no content).   We obviously need to see the errors and serving 200 OK for an error could be very problematic for indexers like Google etc or any wesite monitoring tools (which would not notify us that the site had gone offline).</p>
  
  <p>On our other servers (IIS 7) we see the "yellow error screen" with a message like "could not connect to state server" (or similar). </p>
  
  <p>What could possibly be wrong here? Is there some setting to globablly disable all errors (but this would be stupid if it also serves the 200 status code) or could something else be getting in the way?</p>
  
  <p>The only other thing which could be interfering is we've got ISAPI_Rewrite installed on the server (but this doesn't usually cause this problem).</p>
  
  <p>Thanks!</p>