This is driving me mad.
Please forgive me but I'm not going to post the full code as it is (I believe) irrelevant. The reason behind this is obviously with my code. I was getting the following error:
draggable / droppable dataTransfer is undefined
So I decided to copy the source from:
http://jqueryui.com/droppable/#photo-manager
and I still get the same error.
I am using the latest jQuery UI with all packages included.
Does anyone know why this happens but not on the jQuery UI example?
Regards.
To solve this problem you must add this line:
e.dataTransfer = e.originalEvent.dataTransfer;
before the error line. This should fix it.