Sending the Access-Control-Allow-Origin header allows basic cross-origin access, but calling ASP.NET services like ASMX ScriptServices, ASPX page methods, and WCF services with AspNetCompatibilityRequirements enabled requires your site to respond with one additional CORS header: Access-Control-Allow-Headers

You can configure the same in web.config as follows,

<system.webServer>

  <httpProtocol>

    <customHeaders>

      <add name="Access-Control-Allow-Origin" value="*" />

      <add name="Access-Control-Allow-Headers" value="Content-Type" />

    </customHeaders>

   </httpProtocol>

</system.webServer>