Why am I getting a jQuery 'ui.element is undefined' error?-Collection of common programming errors

I have the following:

$('#widgets ul').sortable(
{
  connectWith: ['#widgets ul'],
  opacity: 0.7,
  start: function(e, ui) {
    fromWidgetPosition = ui.item.prevAll().length + 1;
    fromRowId = ui.element.attr('id');

I just upgraded jQuery from 1.2.6 to 1.3.2, and I also upgraded the jQuery UI library to the latest version.

Originally posted 2013-11-09 22:49:13.