No 'Access-Control-Allow-Origin' header is present (Ember JS)

I am working on an ember app ( Ember 2.11.0 ). Here is my content security policy settings:

contentSecurityPolicy: {
  'default-src': "'none'",
  'script-src': "'self'",
  'font-src': "'self'",
  'connect-src': "'self' 'localhost:4200' 'some-url'",
  'img-src': "'self'",
  'style-src': "'self' *",
  'media-src': "'self'"
}

I am getting the following error when I try to make the following XMLHttpRequest:

XMLHttpRequest cannot load **url-to-sccess**. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.

Any suggestions?