I just got this issue but it only occurred when upgrading a site to PHP 5.6(previously on 5.4).
Warning: in_array() expects parameter 2 to be array, null given in /home2/tabbangy/public_html/tabban/wp-content/plugins/bbpress/includes/common/functions.php on line 1446
I did have Yoast SEO installed but on deactivation the error still persists ( i don’t have NEWS SEO).
Reverting back to 5.4 clears the error.
