AngularJS performs an OPTIONS HTTP request for a cross-origin resource

OPTIONS request are by no means an AngularJS bug, this is how Cross-Origin Resource Sharing standard mandates browsers to behave. Please refer to this document: https://developer.mozilla.org/en-US/docs/HTTP_access_control, where in the "Overview" section it says:

The Cross-Origin Resource Sharing standard works by adding new HTTP headers that allow servers to describe the set of origins that are permitted to read that information using a web browser. Additionally, for HTTP request methods that can cause side-effects on user data (in particular; for HTTP methods other than GET, or for POST usage with certain MIME types). The specification mandates that browsers "preflight" the request, soliciting supported methods from the server with an HTTP OPTIONS request header, and then, upon "approval" from the server, sending the actual request with the actual HTTP request method. Servers can also notify clients whether "credentials" (including Cookies and HTTP Authentication data) should be sent with requests.

It is very hard to provide a generic solution that would work for all the WWW servers as setup will vary depending on the server itself and HTTP verbs that you intend to support. I would encourage you to get over this excellent article (http://www.html5rocks.com/en/tutorials/cors/) that has much more details on the exact headers that needs to be sent by a server.

For Angular 1.2.0rc1+ you need to add a resourceUrlWhitelist.

1.2: release version they added a escapeForRegexp function so you no longer have to escape the strings. You can just add the url directly

'http://sub*.assets.example.com/**' 

make sure to add ** for sub folders. Here is a working jsbin for 1.2: http://jsbin.com/olavok/145/edit

1.2.0rc: If you are still on a rc version, the Angular 1.2.0rc1 the solution looks like:

.config(['$sceDelegateProvider', function($sceDelegateProvider) {
     $sceDelegateProvider.resourceUrlWhitelist(['self', /^https?:\/\/(cdn\.)?yourdomain.com/]);
 }])

Here is a jsbin example where it works for 1.2.0rc1: http://jsbin.com/olavok/144/edit

Pre 1.2: For older versions (ref http://better-inter.net/enabling-cors-in-angular-js/) you need to add the following 2 lines to your config:

$httpProvider.defaults.useXDomain = true;
delete $httpProvider.defaults.headers.common['X-Requested-With'];

Here is a jsbin example where it works for pre 1.2 versions: http://jsbin.com/olavok/11/edit

NOTE: Not sure it works with the latest version of Angular.

ORIGINAL:

It's also possible to override the OPTIONS request (was only tested in Chrome):

app.config(['$httpProvider', function ($httpProvider) {
  //Reset headers to avoid OPTIONS request (aka preflight)
  $httpProvider.defaults.headers.common = {};
  $httpProvider.defaults.headers.post = {};
  $httpProvider.defaults.headers.put = {};
  $httpProvider.defaults.headers.patch = {};
}]);

Your service must answer an OPTIONS request with headers like these:

Access-Control-Allow-Origin: [the same origin from the request]
Access-Control-Allow-Methods: GET, POST, PUT
Access-Control-Allow-Headers: [the same ACCESS-CONTROL-REQUEST-HEADERS from request]

Here is a good doc: http://www.html5rocks.com/en/tutorials/cors/#toc-adding-cors-support-to-the-server

The same document says

Unlike simple requests (discussed above), "preflighted" requests first send an HTTP OPTIONS request header to the resource on the other domain, in order to determine whether the actual request is safe to send. Cross-site requests are preflighted like this since they may have implications to user data. In particular, a request is preflighted if:

It uses methods other than GET or POST. Also, if POST is used to send request data with a Content-Type other than application/x-www-form-urlencoded, multipart/form-data, or text/plain, e.g. if the POST request sends an XML payload to the server using application/xml or text/xml, then the request is preflighted. It sets custom headers in the request (e.g. the request uses a header such as X-PINGOTHER)

When the original request is Get with no custom headers, the browser should not make Options request which it does now. The problem is it generates a header X-Requested-With which forces the Options request. See https://github.com/angular/angular.js/pull/1454 on how to remove this header

This fixed my problem:

$http.defaults.headers.post["Content-Type"] = "text/plain";

If you are using a nodeJS server, you can use this library, it worked fine for me https://github.com/expressjs/cors

var express = require('express')
  , cors = require('cors')
  , app = express();

app.use(cors());

and after you can do an npm update.

Here is the way I fixed this issue on ASP.NET

First, you should add the nuget package Microsoft.AspNet.WebApi.Cors

Then modify the file App_Start\WebApiConfig.cs public static class WebApiConfig { public static void Register(HttpConfiguration config) { config.EnableCors(); ... } }

Add this attribute on your controller class [EnableCors(origins: "*", headers: "*", methods: "*")] public class MyController : ApiController { [AcceptVerbs("POST")] public IHttpActionResult Post([FromBody]YourDataType data) { ... return Ok(result); } }

I was able to send json to the action by this way $http({ method: 'POST', data: JSON.stringify(data), url: 'actionurl', headers: { 'Content-Type': 'application/json; charset=UTF-8' } }).then(...)

Reference : Enabling Cross-Origin Requests in ASP.NET Web API 2

Somehow I fixed it by changing

<add name="Access-Control-Allow-Headers" 
     value="Origin, X-Requested-With, Content-Type, Accept, Authorization" 
     />

to

<add name="Access-Control-Allow-Headers" 
     value="Origin, Content-Type, Accept, Authorization" 
     />

Perfectly described in pkozlowski's comment. I had working solution with AngularJS 1.2.6 and ASP.NET Web Api but when I had upgraded AngularJS to 1.3.3 then requests failed.

Solution for Web Api server was to add handling of the OPTIONS requests at the beginning of configuration method (more info in this blog post): app.Use(async (context, next) => { IOwinRequest req = context.Request; IOwinResponse res = context.Response; if (req.Path.StartsWithSegments(new PathString("/Token"))) { var origin = req.Headers.Get("Origin"); if (!string.IsNullOrEmpty(origin)) { res.Headers.Set("Access-Control-Allow-Origin", origin); } if (req.Method == "OPTIONS") { res.StatusCode = 200; res.Headers.AppendCommaSeparatedValues("Access-Control-Allow-Methods", "GET", "POST"); res.Headers.AppendCommaSeparatedValues("Access-Control-Allow-Headers", "authorization", "content-type"); return; } } await next(); });

If you are using Jersey for REST API's you can do as below

You don't have to change your webservices implementation.

I will explain for Jersey 2.x

1) First add a ResponseFilter as shown below

import java.io.IOException;

import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.container.ContainerResponseFilter;

public class CorsResponseFilter implements ContainerResponseFilter {

@Override
public void filter(ContainerRequestContext requestContext,   ContainerResponseContext responseContext)
    throws IOException {
        responseContext.getHeaders().add("Access-Control-Allow-Origin","*");
        responseContext.getHeaders().add("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");

  }
}

2) then in the web.xml , in the jersey servlet declaration add the below

    <init-param>
        <param-name>jersey.config.server.provider.classnames</param-name>
        <param-value>YOUR PACKAGE.CorsResponseFilter</param-value>
    </init-param>

I gave up trying to fix this issue.

My IIS web.config had the relevant "Access-Control-Allow-Methods" in it, I experimented adding config settings to my Angular code, but after burning a few hours trying to get Chrome to call a cross-domain JSON web service, I gave up miserably.

In the end, I added a dumb ASP.Net handler webpage, got that to call my JSON web service, and return the results. It was up and running in 2 minutes.

Here's the code I used:

public class LoadJSONData : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "text/plain";

        string URL = "......";

        using (var client = new HttpClient())
        {
            // New code:
            client.BaseAddress = new Uri(URL);
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.Add("Authorization", "Basic AUTHORIZATION_STRING");

            HttpResponseMessage response = client.GetAsync(URL).Result;
            if (response.IsSuccessStatusCode)
            {
                var content = response.Content.ReadAsStringAsync().Result;
                context.Response.Write("Success: " + content);
            }
            else
            {
                context.Response.Write(response.StatusCode + " : Message - " + response.ReasonPhrase);
            }
        }
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}

And in my Angular controller...

$http.get("/Handlers/LoadJSONData.ashx")
   .success(function (data) {
      ....
   });

I'm sure there's a simpler/more generic way of doing this, but life's too short...

This worked for me, and I can get on with doing normal work now !!

For an IIS MVC 5 / Angular CLI ( Yes, I am well aware your problem is with Angular JS ) project with API I did the following:

web.config under <system.webServer> node

    <staticContent>
      <remove fileExtension=".woff2" />
      <mimeMap fileExtension=".woff2" mimeType="font/woff2" />
    </staticContent>
    <httpProtocol>
      <customHeaders>
        <clear />
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Allow-Headers" value="Content-Type, atv2" />
        <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS"/>
      </customHeaders>
    </httpProtocol>

global.asax.cs

protected void Application_BeginRequest() {
  if (Request.Headers.AllKeys.Contains("Origin", StringComparer.OrdinalIgnoreCase) && Request.HttpMethod == "OPTIONS") {
    Response.Flush();
    Response.End();
  }
}

That should fix your issues for both MVC and WebAPI without having to do all the other run around. I then created an HttpInterceptor in the Angular CLI project that automatically added in the the relevant header information. Hope this helps someone out in a similar situation.

Little late to the party,

If you are using Angular 7 (or 5/6/7) and PHP as the API and still getting this error, try adding following header options to the end point (PHP API).

 header("Access-Control-Allow-Origin: *");
 header("Access-Control-Allow-Methods: PUT, GET, POST, PUT, OPTIONS, DELETE, PATCH");
 header("Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Authorization");

Note : What only requires is Access-Control-Allow-Methods. But, I am pasting here other two Access-Control-Allow-Origin and Access-Control-Allow-Headers, simply because you will need all of these to be properly set in order Angular App to properly talk to your API.

Hope this helps someone.

Cheers.