wp-includes/load.php:372Dies with a maintenance message when conditions are met.
function wp_maintenance() { // Return if maintenance mode is disabled. if ( ! wp_is_maintenance_mode() ) { return; } if ( file_exists( WP_CONTENT_DIR . '/maintenance.php' ) ) { require_once WP_CONTENT_DIR . '/maintenance.php'; die(); } require_once ABSPATH . WPINC . '/functions.php'; wp_load_translations_early(); header( 'Retry-After: 600' ); wp_die( __( 'Briefly unavailable for scheduled maintenance. Check back in a minute.' ), __( 'Maintenance' ), 503 );}Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/load.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.