Warning: require_once(PEAR.php): failed to open stream: No such file or directory in /usr/local/www/roundcube/vendor/pear/net_smtp/Net/SMTP.php on line 39

Fatal error: require_once(): Failed opening required 'PEAR.php' (include_path='.:/usr/local/share/pear') in /usr/local/www/roundcube/vendor/pear/net_smtp/Net/SMTP.php on line 39