Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires psalm/plugin-phpunit ^0.20.0 -> satisfiable by psalm/plugin-phpunit[0.20.0, 0.20.1]. - Root composer.json requires vimeo/psalm ^6.13.1 -> satisfiable by vimeo/psalm[6.13.1, ..., 6.16.1]. - psalm/plugin-phpunit[0.20.0, ..., 0.20.1] require psalm/psalm-plugin-api ^0.1 -> satisfiable by psalm/psalm-plugin-api[0.1.0]. - psalm/psalm-plugin-api 0.1.0 conflicts with vimeo/psalm <7.0.0. - vimeo/psalm 6.13.1 requires php ~8.1.31 || ~8.2.27 || ~8.3.16 || ~8.4.3 -> your php version (8.5.6) does not satisfy that requirement. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.