Your requirements could not be resolved to an installable set of packages. Problem 1 - phpunit/phpunit[9.3.3, ..., 9.5.x-dev] require ext-dom * -> it is missing from your system. Install or enable PHP's dom extension. - Root composer.json requires phpunit/phpunit ^9.3.3 -> satisfiable by phpunit/phpunit[9.3.3, ..., 9.5.x-dev]. To enable extensions, verify that they are enabled in your .ini files: - /etc/php/7.4/cli/php.ini - /etc/php/7.4/cli/conf.d/10-opcache.ini - /etc/php/7.4/cli/conf.d/10-pdo.ini - /etc/php/7.4/cli/conf.d/20-calendar.ini - /etc/php/7.4/cli/conf.d/20-ctype.ini - /etc/php/7.4/cli/conf.d/20-exif.ini - /etc/php/7.4/cli/conf.d/20-ffi.ini - /etc/php/7.4/cli/conf.d/20-fileinfo.ini - /etc/php/7.4/cli/conf.d/20-ftp.ini - /etc/php/7.4/cli/conf.d/20-gettext.ini - /etc/php/7.4/cli/conf.d/20-iconv.ini - /etc/php/7.4/cli/conf.d/20-json.ini - /etc/php/7.4/cli/conf.d/20-mbstring.ini - /etc/php/7.4/cli/conf.d/20-phar.ini - /etc/php/7.4/cli/conf.d/20-posix.ini - /etc/php/7.4/cli/conf.d/20-readline.ini - /etc/php/7.4/cli/conf.d/20-shmop.ini - /etc/php/7.4/cli/conf.d/20-sockets.ini - /etc/php/7.4/cli/conf.d/20-sysvmsg.ini - /etc/php/7.4/cli/conf.d/20-sysvsem.ini - /etc/php/7.4/cli/conf.d/20-sysvshm.ini - /etc/php/7.4/cli/conf.d/20-tokenizer.ini You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode. I get this error when executing the (new) command in Ubuntu 20 terminal I also use Laravel 8 version. How should I fix this error? thanks