Warning: require(/var/www/html/magento/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php): Failed to open stream: No such file or directory in /var/www/html/magento/vendor/composer/autoload_real.php on line 45

Fatal error: Uncaught Error: Failed opening required '/var/www/html/magento/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php' (include_path='/var/www/html/magento/vendor/magento/zendframework1/library:.:/usr/share/pear:/usr/share/php') in /var/www/html/magento/vendor/composer/autoload_real.php:45 Stack trace: #0 /var/www/html/magento/vendor/composer/autoload_real.php(49): {closure}() #1 /var/www/html/magento/vendor/autoload.php(22): ComposerAutoloaderInit09d167c2f7f677b5531241222631993f::getLoader() #2 /var/www/html/magento/app/autoload.php(51): include('...') #3 /var/www/html/magento/app/bootstrap.php(44): require_once('...') #4 /var/www/html/magento/pub/index.php(12): require('...') #5 {main} thrown in /var/www/html/magento/vendor/composer/autoload_real.php on line 45