Warning: require_once(vendor/autoload.php): Failed to open stream: No such file or directory in /var/www/html/panel/core/config.php on line 3

Fatal error: Uncaught Error: Failed opening required 'vendor/autoload.php' (include_path='.:/usr/local/lib/php') in /var/www/html/panel/core/config.php:3 Stack trace: #0 /var/www/html/panel/core/init.php(7): require() #1 {main} thrown in /var/www/html/panel/core/config.php on line 3