Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires boesing/psalm-plugin-stringf ^1.4 -> satisfiable by boesing/psalm-plugin-stringf[1.4.0]. - boesing/psalm-plugin-stringf 1.4.0 requires php ^7.4 || ~8.0.0 || ~8.1.0 || ~8.2.0 -> your php version (8.3.12) does not satisfy that requirement.