Where is the error coming from?
The error message reports that TablesController::fancybox() could not be found
That means there is a request for a url of the form /tables/fancybox/....
was made.
Most likely this is a 404 request generated by a js library loaded by the page. To identify these errors - simply open e.g. chrome's network panel in developer tools and reload the page. Anything in red indicates a request for something that returned an error - and something to fix.
The information of what is making the request will also be in the apache access/error log - the referer is the initiator responsible for making these erroneous requests.