title: jQuery file upload plugin - fail callback not firing in IE < 10
body: <p>I am using the <a href="https://github.com/blueimp/jQuery-File-Upload" rel="nofollow">https://github.com/blueimp/jQuery-File-Upload</a></p>
  
  <p>It uses XHR file uploads in modern browser and hidden iframe uploads in oldIEs (8,9).</p>
  
  <p>The server returns a 4xx status code (error/fail), when file validation failed.</p>
  
  <pre><code>$('#fileupload').fileupload({
      url: url,
      dataType: 'json',
      done: function (e, data) {
         console.log("done")
      },
      fail: function (e, data) {
         console.log("fail")
      }
  })
  </code></pre>
  
  <p>However in oldIEs the done callback is called even when I send a 4xx status code.
  Is there a way to make it call the fail callback (<a href="https://github.com/blueimp/jQuery-File-Upload/wiki/Options#fail" rel="nofollow">https://github.com/blueimp/jQuery-File-Upload/wiki/Options#fail</a>) and read the response body or statuscode?</p>
  
  <p>I think it might have to do something with the hidden iframe method of uploading the files but I couldn't find anything specific in the docs.</p>