Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^12.0.2 -> satisfiable by phpunit/phpunit[12.0.2, 12.0.x-dev, 12.1.x-dev]. - phpunit/phpunit[12.0.2, ..., 12.1.x-dev] require php >=8.3 -> your php version (8.1.31) does not satisfy that requirement. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.