My custom theme does not load the translations
Change your translate file name to el_GR.po and el_GR.mo: el_GR.po in: testTheme\languages\el.po el_GR.mo in: testTheme\languages\el.mo In 404.php file for print text you should write code like this (add textdomain): <?php _e(‘The requested page does not exist.’, ‘testTheme’); ?> Second parameter is textdomain.