jQuery file upload plugin error <p>I am trying to implement the basic fileupload from blueimp file upload plugin:</p> <p><a href="http://blueimp.github.io/jQuery-File-Upload/basic.html" rel="nofollow">http://blueimp.github.io/jQuery-File-Upload/basic.html</a></p> <p>each time I run the code ,I select 3 files to upload I get this error: Unable to get property 'files' of undefined or null reference.</p> <p>Can anyone help me with this? Thanks</p> <pre><code>var url = 'FileUploadHandler.ashx?upload=start'; $('#fileupload').fileupload({ dataType: 'json', multipart:true, limitMultiFileUploads: 3, url: url, add: function (e, data) { $.each(data.result.files, function (index, file) { $('&lt;p/&gt;').text(file.name).appendTo('#files'); }); data.submit(); }, progressall: function (e, data) { var progress = parseInt(data.loaded / data.total * 100, 10); $('#progress .progress-bar').css( 'width', progress + '%' ); } }).prop('disabled', !$.support.fileInput) .parent().addClass($.support.fileInput ? undefined : 'disabled'); }); </code></pre>