Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^11.0.0 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.4.1]. - Conclusion: don't install nikic/php-parser v4.19.0 (conflict analysis result) - Conclusion: don't install nikic/php-parser v4.17.1 (conflict analysis result) - Conclusion: don't install nikic/php-parser v4.16.0 (conflict analysis result) - Root composer.json requires psalm/plugin-phpunit ^0.18.4 -> satisfiable by psalm/plugin-phpunit[0.18.4]. - Conclusion: don't install vimeo/psalm 5.18.0 (conflict analysis result) - Root composer.json requires vimeo/psalm ^5.18 -> satisfiable by vimeo/psalm[5.18.0, ..., 5.26.1]. - vimeo/psalm 5.19.0 conflicts with nikic/php-parser v4.17.0. - vimeo/psalm 5.19.0 requires nikic/php-parser ^4.16 -> satisfiable by nikic/php-parser[v4.16.0, ..., v4.19.4]. - Conclusion: install one of vimeo/psalm[5.18.0, 5.19.0], nikic/php-parser[v4.16.0, v4.17.1, v4.19.0] (conflict analysis result) Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.