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  • JohanO 2 posts 22 karma points
    Feb 21, 2020 @ 09:15
    JohanO
    0

    CORS problem with API. HTTP OPTIONS call returns 405

    Hi,

    I have added a WebAPI to my Umbraco 8 site, by subclassing UmbracoApiController. Calling the WebAPI using Postman works fine, but when calling it from an external web app it fails. I am getting problems with CORS in the browser. It says OPTIONS {myendpoint} 405 (Method Not Allowed) and Access to {myendpoint} has been blocked by CORS policy: Response to preflight request doesn't pass access control check

    I have modified the web.config file to add the headers required by CORS ('Access-Control-Allow-Origin' and 'Access-Control-Request-Headers') and verified with Postman they are correct. In short:

    • HTTP POST {mysite}/umbraco/api/{mystuff} works fine and has correct CORS headers.
    • HTTP OPTIONS {mysite}/umbraco/api/{mystuff} fails with 405.

    Found this code snippet on how to add CORS, but that code is for Umbraco 7 and doesn't even compile for Umbraco 8.

    Any ideas?

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  • JohanO 2 posts 22 karma points
    Feb 22, 2020 @ 11:16
    JohanO
    0

    Solved the problem!

    Had to do two things.

    1. Add CORS headers to return in web.config
    2. Add [HttpOptions] header to my controller action.

    web.config

    <configuration>
  ...
  <system.webserver>
    ...
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Allow-Headers" value="*" />
        <add name="Access-Control-Allow-Methods" value="GET, POST, OPTIONS" />
        <add name="Access-Control-Max-Age" value="86400" />
      </customHeaders>
    </httpProtocol>

    MyController.cs

    public class MyController : UmbracoApiController
{
    [HttpPost]
    [HttpOptions]
    public Task<IHttpActionResult> MyMethod()
    {
        ...
    }
}
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