Your requirements could not be resolved to an installable set of packages. Problem 1 - phpunit/phpunit[dev-main, 11.1.0, ..., 11.3.1] require php >=8.2 -> your php version (8.1.29) does not satisfy that requirement. - phpunit/phpunit 11.4.x-dev is an alias of phpunit/phpunit dev-main and thus requires it to be installed too. - Root composer.json requires phpunit/phpunit ^11.1 -> satisfiable by phpunit/phpunit[11.1.0, ..., 11.4.x-dev (alias of dev-main)].