admin/environment/php extension/fileinfo

From MoodleDocs

The Fileinfo PECL package has been superseded, but is still maintained for bugs and security fixes. Indeed, the fileinfo extension has been moved to php sources [php-src/ext/fileinfo] since 5.3.0: you should enable it, since it should be already installed by default with your PHP installation. Look for more specific details for your OS environment and/or contact your Hosting Provider.