Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpstan/phpstan-phpunit ^2.0.1 -> satisfiable by phpstan/phpstan-phpunit[2.0.1]. - phpstan/phpstan-phpunit 2.0.1 requires phpstan/phpstan ^2.0 -> found phpstan/phpstan[2.0.0, 2.0.1] but it conflicts with your root composer.json require (^1.12.10). Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.