Transferier my existing settings to a new installation

PHP Fatal error: Class 'Backup' not found in /var/lib/asterisk/bin/backup.php on line 40
Whoops\Exception\ErrorException: Class 'Backup' not found in file /var/lib/asterisk/bin/backup.php on line 40
Stack trace:
1. () /var/lib/asterisk/bin/backup.php:40