Application using CORS does not work in Azure
<p>I have configured my application to use CORS. All works perfectly in my local environment, but after deploying the app to Azure, we receive the following error:</p>

<blockquote>
  <p>No 'Access-Control-Allow-Origin' header is present on the requested
  resource.</p>
</blockquote>

<p>When I run the application on my computer and create the origin header using the DHC chrome extension, it does actually work:</p>

<pre><code>Access-Control-Allow-Credentials:   true
Access-Control-Allow-Origin:        http://mysite.s3-website-eu-west-1.amazonaws.com
Access-Control-Expose-Headers:      Location,Finished
</code></pre>

<p>This is the code/configuration that I use: </p>

<p><strong>Global.asax.cs</strong></p>

<pre><code>protected void Application_Start()
{
    GlobalConfiguration.Configure(WebApiConfig.Register);
}
</code></pre>

<p><strong>WebApiConfig.cs</strong></p>

<pre><code>public static void Register(HttpConfiguration config)
{
    config.EnableCors(new MyCorsPolicyAttribute());
    config.MapHttpAttributeRoutes();
}
</code></pre>

<p><strong>MyCorsPolicyAttribute.cs</strong></p>

<pre><code>public class MyCorsPolicyAttribute : Attribute, ICorsPolicyProvider
{
    private CorsPolicy _policy;

    public MyCorsPolicyAttribute()
    {
        _policy = new CorsPolicy
        {                
            AllowAnyMethod = true,
            AllowAnyHeader = true,
            SupportsCredentials = true
        };

        _policy.ExposedHeaders.Add("Location");
        _policy.ExposedHeaders.Add("Finished");

        // Add allowed origins.
        _policy.Origins.Add("http://mysite.s3-website-eu-west-1.amazonaws.com");
        _policy.Origins.Add("http://localhost:81");//for testing purposes; 
   }
    public Task&lt;CorsPolicy&gt; GetCorsPolicyAsync(HttpRequestMessage request)
    {
        return Task.FromResult(_policy);
    }

    public Task&lt;CorsPolicy&gt; GetCorsPolicyAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        return Task.FromResult(_policy);
    }   
}
</code></pre>

<p>and finally the <strong>web.config</strong></p>

<pre><code>&lt;system.webServer&gt;
  &lt;handlers&gt;
    &lt;remove name="ExtensionlessUrlHandler-Integrated-4.0" /&gt;
    &lt;remove name="WebDav" /&gt;
    &lt;remove name="OPTIONSVerbHandler" /&gt;
    &lt;remove name="TRACEVerbHandler" /&gt;
    &lt;add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" /&gt;
  &lt;/handlers&gt;
&lt;/system.webServer&gt;
</code></pre>

<p>Why doesn't the above work in the Azure enviroment?</p>