Missing token 'access-control-allow-headers' in CORS header 'Access-Control-Allow-Headers' from CORS preflight channel

Question

I have two VS projects : one exposing MVC5 controllers, the other being an angular client. I want the angular client to be able to query the controllers. I read numerous thr

Answer 1

I tried in my .net c# mvc app and client app in angular 8 but it is not working. IN web.config, i added

In global.axax.cs file also, i added

    void MvcApplication_AuthenticateRequest(object sender, EventArgs e)
    {
        Context.Response.AddHeader("Access-Control-Allow-Origin", "http://localhost:4200");
    }

but it is not working. In chrome in response header it does show as :

Access-Control-Allow-Headers: Content-Type Access-Control-Allow-Origin: http://localhost:4200 Access-Control-Allow-Origin: http://localhost:4200

but in request header it shows as

Access-Control-Request-Headers: access-control-allow-origin,content-type,x-iphoneclientid

whereas it needs to have like

x-iphoneclientid : 8E72FF50-548B

since x-iphoneclientid is the token i validate in my filter class as

    protected override System.Threading.Tasks.Task SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
    {

        if (request == null || request.RequestUri == null)
        {
            return null;
        }
        // Write your Authentication code here
        IEnumerable monsterApiKeyHeaderValues = null;

        // Checking the Header values
        if (request.Headers.TryGetValues("x-iphoneclientid", out monsterApiKeyHeaderValues))

and above condition does not find so it rejects it and it does not reach to controller.

I even have put following in my controller

[EnableCors("", "", "*")]

can you guide please

Thanks