Cross-Origin Request Blocked in Firefox only! [OPTIONS : 403 Forbidden] - amazon-web-services

Question

It's a CORS problem again
[and I don't have much knowledge about CORS].
My environment :
I have JSON file stored in Amazon S3 server, and reading this JSON file from my web application.
My issue :
I am getting this in FireFox only
Cross-Origin Request Blocked: The Same Origin Policy disallows reading
the remote resource at server. (Reason: CORS header
‘Access-Control-Allow-Origin’ missing)
Note : I have configured CORSRule in the server [Amazon S3]; after that, Chrome and other browsers work properly, but Firefox gives this error.
In Firefox Network tab [inspect element]:
Status : 403
Method : OPTIONS
Cause : xhr
Type : xml
Request Headers :
Host: myWebApp.net
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:49.0) Gecko/20100101 Firefox/49.0
Accept: text/plain, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
X-Requested-With: XMLHttpRequest
Referer: https://myWebApp.net/page.jsp
Connection: keep-alive
Response Headers :
Content-Length: 0
Date: Thu, 24 Nov 2016 07:27:30 GMT
Location: https://webApp.s3.amazonaws.com/file.json
Server: Apache-Coyote/1.1
I have looked around but didn't find any causes.
So I need your help.
As it works properly in the Chrome browser, the issue is in Firefox only.
Please describe step by step if possible [I am new to these things].

Answer 1

Opps!
Finally got solution.
The issue was in Amazon S3's CORSConfiguration
I don't know much about it, but now its allowing Cross-Origin from all browsers.
I have changes CORSConfiguration as :
<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
<AllowedOrigin>https://myWebApp.net</AllowedOrigin>
<AllowedMethod>GET</AllowedMethod>
<AllowedMethod>POST</AllowedMethod>
<AllowedMethod>PUT</AllowedMethod>
<AllowedHeader>*</AllowedHeader>
<MaxAgeSeconds>3000</MaxAgeSeconds>
<ExposeHeader>x-amz-server-side-encryption</ExposeHeader>
<ExposeHeader>x-amz-request-id</ExposeHeader>
<ExposeHeader>x-amz-id-2</ExposeHeader>
</CORSRule>
</CORSConfiguration>
by this rules, browsers getting proper Request Headers and Response Headers.
Request Headers :
Host: myWebApp.s3.amazonaws.com
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:49.0) Gecko/20100101 Firefox/49.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Access-Control-Request-Method: GET
Access-Control-Request-Headers: x-requested-with
origin: https://myWebApp.net
Connection: keep-alive
Cache-Control: max-age=0
Response Headers :
Access-Control-Allow-Headers: x-requested-with
Access-Control-Allow-Methods: GET, POST, PUT
Access-Control-Allow-Origin: https://myWebApp.net
Access-Control-Max-Age: 3000
Content-Length: 0
Date: Thu, 24 Nov 2016 13:21:17 GMT
Server: AmazonS3
Vary: Origin, Access-Control-Request-Headers, Access-Control-Request-Method
access-control-allow-credentials: true
access-control-expose-headers: x-amz-server-side-encryption, x-amz-request-id, x-amz-id-2
x-amz-id-2: emYYMILNIdkCejpjuDXz4Haks87asdhj/7JL5AASt/8eIwKdgO1Gb/AzGRg7SU/GH55IVopScg=
x-amz-request-id: 307572CDFF39F443