The Symfony Installer is not compatible with Symfony 4.x or newer versions. Run this other command to install Symfony using Composer instead: composer create-project symfony/skeleton test code example
Example 1: create new project symfony
# run this if you are building a traditional web application
$ symfony new my_project_name --full
# run this if you are building a microservice, console application or API
$ symfony new my_project_name
Example 2: symfony install website skeleton
# run this if you are building a traditional web application
composer create-project symfony/website-skeleton my_project_name