Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpstan/extension-installer 1.3.1 -> satisfiable by phpstan/extension-installer[1.3.1]. - phpstan/extension-installer 1.3.1 requires phpstan/phpstan ^1.9.0 -> found phpstan/phpstan[1.9.0, ..., 1.12.12] but it conflicts with your root composer.json require (2.0.3). Problem 2 - Root composer.json requires phpstan/phpstan-deprecation-rules 1.1.4 -> satisfiable by phpstan/phpstan-deprecation-rules[1.1.4]. - phpstan/phpstan-deprecation-rules 1.1.4 requires phpstan/phpstan ^1.10.3 -> found phpstan/phpstan[1.10.3, ..., 1.12.12] but it conflicts with your root composer.json require (2.0.3). Problem 3 - Root composer.json requires phpstan/phpstan-phpunit 1.3.15 -> satisfiable by phpstan/phpstan-phpunit[1.3.15]. - phpstan/phpstan-phpunit 1.3.15 requires phpstan/phpstan ^1.10 -> found phpstan/phpstan[1.10.0, ..., 1.12.12] but it conflicts with your root composer.json require (2.0.3). Problem 4 - Root composer.json requires phpstan/phpstan-strict-rules 1.5.2 -> satisfiable by phpstan/phpstan-strict-rules[1.5.2]. - phpstan/phpstan-strict-rules 1.5.2 requires phpstan/phpstan ^1.10.34 -> found phpstan/phpstan[1.10.34, ..., 1.12.12] but it conflicts with your root composer.json require (2.0.3). Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.