Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires infection/infection ^0.27.11 -> satisfiable by infection/infection[0.27.11]. - Root composer.json requires phpunit/phpunit ^9.6.22 -> satisfiable by phpunit/phpunit[9.6.22]. - phpunit/phpunit 9.6.22 requires phpunit/php-code-coverage ^9.2.32 -> satisfiable by phpunit/php-code-coverage[9.2.32]. - Root composer.json requires vimeo/psalm ^6.0.0 -> satisfiable by vimeo/psalm[6.0.0]. - Conclusion: don't install nikic/php-parser v4.15.1 (conflict analysis result) - infection/infection 0.27.11 requires nikic/php-parser ^4.15.1 -> satisfiable by nikic/php-parser[v4.15.1, ..., v4.19.4]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.13.0, ..., v4.19.4, v5.0.0, ..., v5.4.0]. - phpunit/php-code-coverage 9.2.32 requires nikic/php-parser ^4.19.1 || ^5.1.0 -> satisfiable by nikic/php-parser[v4.19.1, v4.19.2, v4.19.3, v4.19.4, v5.1.0, ..., v5.4.0]. - Conclusion: don't install nikic/php-parser v4.19.1 (conflict analysis result) Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.