[@robin-w Moderator 9 years, 2 months ago]

Suspect you are using php 7.1
so 3 fixes
1. downgrade to a lesser version of php
2. upgrade to bbpress 2.6rc3
3. in bbpress 2.5.13 in includes/forums/functions.php
change line 1851 from
$meta_query = $posts_query->get( ‘meta_query’ );
to
$meta_query = $posts_query->get( ‘meta_query’, array() );
and change line 1796 from
$post_stati = $posts_query->get( ‘post_status’ );

to

$post_stati = $posts_query->get( ‘post_status’ );
if (!is_array($post_stati)){
$post_stati = array($post_stati);
}