After a fresh install with WordPress 3.6 and ACF 18.104.22.168 and
WP_DEBUG set to
true, I started to see this php message on every page of WordPress backend:
Strict Standards: Declaration of acf_taxonomy_field_walker::start_el() should be compatible with Walker::start_el(&$output, $object, $depth = 0, $args = Array, $current_object_id = 0) in ../wp-content/plugins/advanced-custom-fields/core/fields/taxonomy.php on line 471
Edit: Took a closer look now and the error disappears if in file
taxonomy.php line 408
function start_el( &$output, $term, $depth, $args = array(), $current_object_id = 0)
is changed to
function start_el( &$output, $term, $depth = 0, $args = array(), $current_object_id = 0)
Edit 2: There are more Strict Standards error messages caused by e.g.
_functions.php when the fields are displayed on a page or post edit page in backend, please publish a fixed version, thanks.