Jak naprawić ten błąd?
Fatal error: Uncaught Error: Undefined constant "MB_OVERLOAD_STRING" in /var/www/libraries/vendor/joomla/string/src/phputf8/utf8.php:38 Stack trace: #0 /var/www/libraries/vendor/composer/autoload_real.php(66): require() #1 /var/www/libraries/vendor/composer/autoload_real.php(56): composerRequire205c915b9c7d3e718e7c95793ee67ffe() #2 /var/www/libraries/vendor/autoload.php(7): ComposerAutoloaderInit205c915b9c7d3e718e7c95793ee6 7ffe::getLoader() #3 /var/www/libraries/cms.php(36): require('...') #4 /var/www/installation/application/framework.php(39): require_once('...') #5 /var/www/installation/application/bootstrap.php(17): require_once('...') #6 /var/www/installation/index.php(29): require_once('...') #7 {main} thrown in /var/www/libraries/vendor/joomla/string/src/phputf8/utf8.php on line 38

wywala mi ten blad jak próbuje odwiedzić http://127.0.0.1/installation/ llub http://127.0.0.1/

ubuntu 20.04
nginx
php 8.0.2