when i upload image in cakephp through ajax cake-error received

I am trying to upload image in cakephp through ajax everything looks good but when i click select image the page give error in popup box like in image

my view code is

                    

                    
                        
">
                            
                                " onchange="upload();" class="browse" type="file" name="myfile[]">
                            
                            webroot?>images/ajax-loader.gif" class="img_loader" id="img_loader" style="display:none;">
                        
                    

                    
                
            </div>
            
                function upload($data){
                    //alert($data);
                     file_data = jQuery('#browse'+$data).prop("files")[0];
                    /* var id = 'browse'+$data;
                    alert('browse'+$data);
                    var fileInput = document.getElementById(id);
                    var file_data = fileInput.files[0]; */

                    jQuery.ajax({
                        type: "POST",
                        url: "webroot?>index/upload",
                        data: "file="+file_data,
                        cache: false,
                        success: function($resasas)
                            {
                                alert($resasas);
                            }
                        });
                }
            

i doesn't recognize this error please help .this is only uploading error not submit.