Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpstan/phpstan ^2.0 -> satisfiable by phpstan/phpstan[2.0.0, 2.0.1, 2.0.2, 2.0.3]. - phpstan/phpstan[2.0.0, ..., 2.0.3] require php ^7.4|^8.0 -> your php version (7.3.33) does not satisfy that requirement.