HTML it is not actually valid in 2.0.1

In framework/core/subsystems/expTheme.php around line 300 function headerInfo change from:

    if(empty($config['xhtml'])||($config['xhtml']==true)){
        define("XHTML",1);define("XHTML_CLOSING",""); //default
    } else {
        define("XHTML",0); define("XHTML_CLOSING","/");
    }

to:

    if(isset($config['xhtml']) && $config['xhtml']==true){
        define("XHTML",1);define("XHTML_CLOSING","/"); //default
    } else {
        define("XHTML",0); define("XHTML_CLOSING","");
    }

Also in expTheme for favicon.ico include, at the end replace with:

    '.XHTML_CLOSING.'

In framework/core/subsystems/expCSS.php line 106 change the end to:

    $link . '"' . XHTML_CLOSING.'>'."\r\n";