Today I got this error which surprised me for a little while. I was pretty sure I had it before, but could not find a reference, so I decided to put it here for sure this time!

Error: this.table.tBodies is undefined
Source File: http://linux.m2osw.com/sites/all/modules/jquery_update/replace/tabledrag...
Line: 516

Whenever I create a table in Drupal and the elements can be sorted, I like to use the drupal_add_tabledrag() feature. This function first parameter is the name of the table to drag. I was totally sure I had it right but it just kept giving me that error, over and over again while trying to drag the items.

Finally, I looked closer in the HTML and noticed that the form was actually given the exact name I was trying to assign to the table (an identifier; id="my-table"). Changing the name of the table fixed the problem at once.