Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^5.7 -> satisfiable by phpunit/phpunit[5.7.0, ..., 5.7.27]. - phpunit/phpunit[5.7.0, ..., 5.7.27] require php ^5.6 || ^7.0 -> your php version (8.1; overridden via config.platform, actual: 8.1.30) does not satisfy that requirement.