Has this version been tested with BuddyPress? I have a BuddyPress PageLines site. I tested this upgrade on the WP Engine Staging server and the /groups/ and /members/ and /forums/ were all just gone -- blank white page. No WP_DEBUG errors. No difference after deactivating all but BuddyPress, BP Template Pack, and BP for PageLines. No difference when switching from child theme to parent theme. Only difference is if I deactivated all (including BP) plugins, in which case I got a page that just said "Groups" or "Members" or "Forums".