CODEWITHSUNDEEP
c#web-servicescors
Florian Berger
Florian Berger

Reputation: 327

RESTful WebService CORS Preflight Channel did not succeed

I created a WebService in C#. All GET methods are working without any problems.

Now I need to provide some POST methods. When calling it via C# it works without any problems. Then I tried to write a small html page with JavaScript to call my methods. But there I get a CORS error ("Preflight channel did not succeed").

I already added the following part to my web.config file:

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

Sadly it is still not working. What am I doing wrong?

Upvotes: 1

Views: 2453

Answers (1)

CodingGorilla
CodingGorilla

Reputation: 19842

So what you have here is not really a valid way to handle CORS requests. The problem is that this will add the CORS headers to all responses, but browsers will use an OPTIONS request in order to check for CORS headers. This would work if you also implement OPTIONS requests for all of your API end points.

The better option is to use one of the CORS frameworks, such as this one: Enabling Cross-Origin Requests in ASP.NET Web API 2 for ASP.NET WebAPI 2. This type of framework will intercept the OPTIONS request for you and supply the appropriate response without the need for you to manually create 2 routes per endpoint.

Upvotes: 4

Related Questions