我使用此挂钩将网站置于维护模式functions.php,

function activate_maintenance_mode() {
    //If the current user is NOT an \'Administrator\' or NOT \'Super Admin\' then display Maintenance Page.
    if ( !(current_user_can( \'administrator\' ) ||  current_user_can( \'super admin\' ))) {
        //Kill WordPress execution and display HTML maintenance message. 
        wp_die(\'<h1>Sitio en mantenimiento</h1><p>Nuestro sitio esta actualemente en mantenimiento. 
            <br /><strong>Ya volvemos!</strong></p>\', \'mantenimiento\');
    }
}
//Hooks the \'activate_maintenance_mode\' function on to the \'get_header\' action.
add_action(\'get_header\', \'activate_maintenance_mode\');

EDIT: 问题是W3 Total Cache插件。