Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit 11.5.2 -> satisfiable by phpunit/phpunit[11.5.2]. - vimeo/psalm[5.26.0, ..., 5.x-dev] require nikic/php-parser ^4.17 -> satisfiable by nikic/php-parser[v4.17.0, ..., 4.x-dev]. - vimeo/psalm 5.25.0 requires nikic/php-parser ^4.16 -> satisfiable by nikic/php-parser[v4.16.0, ..., 4.x-dev]. - Conclusion: don't install one of nikic/php-parser[v5.4.0], vimeo/psalm[5.26.1] | install nikic/php-parser[v4.17.0] (conflict analysis result) - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.0.0alpha1, ..., 4.x-dev, v5.0.0alpha1, ..., v5.4.0]. - Conclusion: install nikic/php-parser v5.4.0 (conflict analysis result) - Root composer.json requires vimeo/psalm ^5.25 -> satisfiable by vimeo/psalm[5.25.0, 5.26.0, 5.26.1, 5.x-dev]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.