I was working on getting the Swiff uploader working with a wedding vendors application and was getting the following javascript error:

__flash__argumentsToXML is not defined

After banging my head for a while (the exact same code was working fine on another website) I discovered the problem. It was a really silly oversight on my part. I didn’t have the file Swiff.Uploader.swf in the right location!!!

Make sure that when create a swiffy object you have a the above swiff file where you set it in the path:

    $('upload-fallback').removeClass('hide');
  	var swiffy = new Fancyuploader2($('upload-status'), $('upload-list'), {
  	...
        /* This is the important bit re: this blog post */
  		'path': '/swf/Swiff.Uploader.swf',
  	...
  		'target': 'upload-browse-images', /* This is for flash 10 */
  		'onLoad': function() {
  			$('upload-status').removeClass('hide');
  			$('upload-fallback').destroy();
  		}

  	});