I'm trying Building your own Framework with the MicroKernelTrait from: https://symfony.com/doc/current/configuration/micro_kernel_trait.html

composer require symfony/config symfony/http-kernel \
  symfony/http-foundation symfony/routing \
  symfony/dependency-injection symfony/framework-bundle

This run success and created a index.php as per doc and copy pasted the code (<?php ... )

Then symfony server:start => server starts with no problem. But when i go to http://localhost:8000/random/10 .