Error on Homepage: "function '' not found or invalid function name"

I’m getting the following error on the homepage of a WordPress site I’m working on.

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '' not found or invalid function name in /home/artattac/public_html/wp-includes/plugin.php on line 496

I did some Googling and searching here on the forums and found others reporting similar problems, but I have not found an answer that has worked for me yet. I tried disabling the plugins, but the error remained. It went away when I changed the them from a child version of Grove to Twenty Twelve, so I’m guessing it is an issue with the them. Since the function seems to be unnamed, I’m just not sure what to look for and remove.