The OPTIONS request is a normal request: this is used to ask for permissions relative to CORS restrictions. Have a look to this page to understand how CORS work under the hood.
In your case, this is a pure CORS related issue. The OPTIONS request contains this header:
Access-Control-Request-Headers: authorization,cache-control,x-requested-with
Which means: can I use "authorization", "cache-control" and "x-requested-with" headers in my cross-domain AJAX request ?
The response you get is the following:
Access-Control-Allow-Headers :"Authorization, Content-Type, Accept, X-Mashape-Authorization"
Which means: you're allowed to use those headers only: "Authorization", "Content-Type", "Accept", and "X-Mashape-Authorization".
As you can see, "cache-control" and "x-requested-with" are not listed in the allowed list, causing the browser to reject the request.
I've come to 2 test code sample which show this behavior:
Example 1 (working)
var data = new FormData();
data.append('image', 'http://placehold.it/300x500');
var xhr = new XMLHttpRequest();
xhr.open('POST', 'https://api.imgur.com/3/upload', true);
xhr.setRequestHeader('Authorization', 'Client-ID xxxxxxxxxx');
xhr.send(data);
Here are the preflight request's headers sent when running this code (as shown by Firefox 30 devtools, and I've removed unrelated headers such as User-Agent, Accept ...):
And the corresponding response's headers
- access-control-allow-origin :"*"
- Access-Control-Allow-Methods :"GET, PUT, POST, DELETE, OPTIONS"
- Access-Control-Allow-Headers :"Authorization, Content-Type, Accept, X-Mashape-Authorization"
Here, we can see that we prompt access to the "authorization" header, and the server is accepting this header, allong with the POST method and any origin URL, so the CORS requirements are satisfied and the request is allowed by the browser.
Example 2 (not working)
var data = new FormData();
data.append('image', 'http://placehold.it/300x500');
var xhr = new XMLHttpRequest();
xhr.open('POST', 'https://api.imgur.com/3/upload', true);
xhr.setRequestHeader('Authorization', 'Client-ID xxxxxxxxxx');
// the only difference with the previous code is this line
xhr.setRequestHeader('Cache-Control', 'no-cache');
xhr.send(data);
Preflight request's headers:
Preflight response's headers (which is the same as in example 1):
- access-control-allow-origin :"*"
- Access-Control-Allow-Methods :"GET, PUT, POST, DELETE, OPTIONS"
- Access-Control-Allow-Headers :"Authorization, Content-Type, Accept, X-Mashape-Authorization"
Here, the "Access-Control-Request-Headers" header prompt access for "cache-control", which the server does not provide, so the CORS requirements are not satisfied and the request is rejected by the browser.
Here's a JSFiddle referencing different working and not working demos for your problem: http://jsfiddle.net/pomeh/Lfajnebh/. Pay attention to details to understand what's going on, there is few comments but they are here to emphasis trickiest parts of the code.
As a bonus, I've sent a pull request to DropZone's GitHub repository to fix this problem (https://github.com/enyo/dropzone/pull/685) which allows you to remove pref-defined headers by DropZone. Give it a try:
var myDropzone = new Dropzone('.dropzone', {
//...
headers: {
'Authorization': authorizationHeader,
// remove Cache-Control and X-Requested-With
// to be sent along with the request
'Cache-Control': null,
'X-Requested-With': null
}
});
The code above should work with my patched version (https://github.com/pomeh/dropzone/commit/f0063db6e5697888582421865840258dec1ffdc1), whereas the code above should not:
var myDropzone = new Dropzone('.dropzone', {
//...
headers: {
'Authorization': authorizationHeader,
// remove Cache-Control and X-Requested-With
// to be sent along with the request
}
});
imagename in the request ? If you really want to upload a file, you look into AJAX file upload handling (Google it). – LacrimatoryAccess-Control-Allow-Originheader in the response so it might be related... But you can't change that anyway. That look strange this header is missing. Also, be sure to have the correctContent-Typeasmultipart/form-datato handle the file upload. Finally, here's the link I messed up in my previous comment: html5rocks.com/en/tutorials/cors/… Have a look to it to understand how CORS work, maybe you'll find some useful information in there. Edit: what's the exact domain name where the request comes from ? – Lacrimatorymy.opencubes.iowhich does not exist but in myhostsfile – Cajolery