include(../template/header.html): failed to open stream: No such file or dir

引入路径的问题，建议加入

nclude  $_SERVER['DOCUMENT_ROOT']."/template/header.html";

意思是获取网站根目中的include.php.

        //这是错误的用法
        // include('../template/header.html');
        // 这是正确的用法
        include $_SERVER['DOCUMENT_ROOT']."/template/header.html";