AngularJS $http.post error in Internet Explorer &l

I have the following bit of code, which works fine in every modern browser, but fails in Internet Explorer 9 and below.

authService.login = function(credentials) {
  return $http.post('https://example.com/login', credentials).then(function(res) {
    return res;
  }, function(err) {
    return err;
  });
};

credentials is an object that looks like this:

{
  username: 'john@example.com',
  password: 'smith'
}

The problem is that the POST never actually happens, instead it jumps straight to return err; and no error is even set. It says Impossible d'effectuer l'opération à cause de l'erreur suivante c00c023e.. The key being c00c023e, which is supposedly an encoding problem, but I don't see how that would completely prevent the call from happening.

The 'fix' is to use $http.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded'; which does allow IE to POST, but my backend expects JSON so that doesn't help.

I'm using AngularJS 1.2.22.

Any ideas?

Comments led me in the right direction, this was indeed a CORS issue. Turns out there is a simple and library agnostic fix provided by the XDomain library.

In the app making the CORS request, include the following script before any other scripts:

<!--[if lte IE 9]>
    <script src="http://example.com/xdomain/xdomain.min.js" data-slave="http://example.com/xdomain/proxy.html"></script>
<![endif]-->

Then, on the example.com domain, copy xdomain.min.js and create the proxy.html file that was defined above in the data-slave attribute. The proxy file must contain:

<!DOCTYPE html>
<script src="xdomain.min.js" data-master="https://subdomain.example.com"></script>

Cross-domain requests will now work properly in IE9 and below. You could use XDomain for every browser rather than just IE by removing the conditional comment, but I doubt there is a significant portion of users using a browser that doesn't support CORS that also isn't Internet Explorer.