Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires psalm/plugin-phpunit ^0.13 -> satisfiable by psalm/plugin-phpunit[0.13.0]. - psalm/plugin-phpunit 0.13.0 requires php ^7.3 || ^8.0 -> your php version (7.2.34) does not satisfy that requirement. Problem 2 - Root composer.json requires maglnet/composer-require-checker ^4.11 -> satisfiable by maglnet/composer-require-checker[4.11.0]. - maglnet/composer-require-checker 4.11.0 requires php ~8.2.0 || ~8.3.0 -> your php version (7.2.34) does not satisfy that requirement.