equire(/storage/ssd4/589/16076589/public_html/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php): failed to open stream: No such file or directory in /storage/ssd4/589/16076589/public_html/vendor/composer/autoload_real.php on line 71 code example

Example: PHP Warning: require(/Applications/Ampps/www/SalesSystem/vendor/composer/../symfony/polyfill-php80/bootstrap.php): failed to open stream: No such file or directory in /Applications/Ampps/www/SalesSystem/vendor/composer/autoload_real.php on line 66

$ composer dump-autoload
  
 #if php artisan not installed, execute following command
$ php artisan install