Moto-Zulli

This is getting old. here is the best idea yet. Replace the line with:

if ( is_array ($_current_page->ancestors) && in_array ( $page->ID, $_current_page->ancestors ) )

Well, in my desperation, I failed to look at what that line is doing. Just comment the whole line out; all the line does is to insert a css class. If your formatting depends on the “current_page_ancestor” css class, you may have problems, but otherwise, you should be ok.

I am having the same problem with a network site after the client updated to 3.5; update to 3.5.1 had no effect. I have a temporary hack that might work for you, too:

On line 1039 of post-template.php, I replaced the function in_array with isset and the problem has disappeared.

Altering core files is a no-no, but I’m desperate. If you get this message, please let me know how it works for you, and I’ll report the problem to the dev team.