Warning: require_once(/var/www/html/vendor/autoload.php): failed to open stream: No such file or directory in /var/www/html/index.php on line 2

Fatal error: require_once(): Failed opening required '/var/www/html/vendor/autoload.php' (include_path='.:/usr/local/lib/php') in /var/www/html/index.php on line 2