WordPress at a glance
filter is not described

pre_handle_404 filter-hook . WP 4.5.0

Filters whether to short-circuit default header status handling.

Returning a non-false value from the filter will short-circuit the handling and return early.

Usage

add_filter( 'pre_handle_404', 'filter_function_name_9630', 10, 2 );
function filter_function_name_9630( $preempt, $wp_query ){
	// filter...

	return $preempt;
}
$preempt(true/false)
Whether to short-circuit default header status handling.
Default: false
$wp_query(WP_Query)
WordPress Query object.

Where the hook is called

WP::handle_404()
wp-includes/class-wp.php 633
if ( false !== apply_filters( 'pre_handle_404', false, $wp_query ) ) {

Where the hook is used (in WP core)

Does not used.