API Gateway CORS: no 'Access-Control-Allow-Origin' header

Question

Although CORS has been set up through API Gateway and the Access-Control-Allow-Origin header is set, I still receive the following error when attempting to call the API from AJAX within Chrome:

XMLHttpRequest cannot load http://XXXXX.execute-api.us-west-2.amazonaws.com/beta/YYYYY. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 403.

I attempted to GET the URL through Postman and it shows the above header is successfully passed:

And from the OPTIONS reponse:

How can I call my API from the browser without reverting to JSON-P?

Answer 1

I get the same problem. I have used 10hrs to findout.

https://serverless.com/framework/docs/providers/aws/events/apigateway/

// handler.js

'use strict';

module.exports.hello = function(event, context, callback) {

const response = {
  statusCode: 200,
  headers: {
    "Access-Control-Allow-Origin" : "*", // Required for CORS support to work
    "Access-Control-Allow-Credentials" : true // Required for cookies, authorization headers with HTTPS 
  },
  body: JSON.stringify({ "message": "Hello World!" })
};

callback(null, response);
};