title: pre flight HTTP OPTIONS call timesout with 500 Error sporadically
body: <p>I have a C# based webAPI hosted on Azure WebApp.
  Sporadically, the HTTP OPTIONS call fails with a 500 error.</p>
  
  <p>The OPTIONS call is not handled by our code. So I assume the server handles it by itself.</p>
  
  <p>I tried enabling logs but both event log and web server logs does not print anything other than that it failed with a 500 error.</p>
  
  <p>Any ideas why this would happen?.</p>
  
  <p><strong>Update:</strong>
  I see only the below error messages in the web server logs. No details 
  Additionally I added code in my webAPI to handle options call, but the code does not go there. Not sure if I need to enable/disable something in web.confi.</p>
  
  <p>2017-08-31 11:49:39 xxx.mywebsite.com OPTIONS /api/apiname StartDate=2017-08-25&amp;EndDate=2017-08-31&amp;X-ARR-LOG-ID=d86ffe7f-32c9-410b-8116-65833d5af7b9 443 - xxx.xxx.xxx.xxx Mozilla/5.0+(Windows+NT+6.1;+Win64;+x64)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/60.0.3112.113+Safari/537.36 - www.website.com  500 121 0 636 1612 230013</p>