title: CORS error when fetching api from its own domain
body: <p>One of app users constantly has an error when trying to fetch api from the same domain. This error occurs in Chrome only, other browsers are OK at his computer. He also tried to install Chrome CORS extention, but no luck. Does anybody has any idea why this might happen?</p>
  
  <p>Error text below: </p>
  
  <p>Failed to load <a href="http://my-app.com/api/v1/scoreboard" rel="nofollow noreferrer">http://my-app.com/api/v1/scoreboard</a>: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '<a href="http://www.my-app.com" rel="nofollow noreferrer">http://www.my-app.com</a>' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.</p>