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 vimeo/psalm ^5.26.1|^6.2 -> satisfiable by vimeo/psalm[5.26.1, 6.2.0]. - infection/infection 0.27.11 requires nikic/php-parser ^4.15.1 -> satisfiable by nikic/php-parser[v4.15.1, ..., v4.19.4]. - vimeo/psalm 5.26.1 requires php ^7.4 || ~8.0.0 || ~8.1.0 || ~8.2.0 || ~8.3.0 -> your php version (8.4.3) does not satisfy that requirement. - vimeo/psalm 6.2.0 requires nikic/php-parser ^5.0.0 -> satisfiable by nikic/php-parser[v5.0.0, ..., v5.4.0]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.10.0, ..., v4.19.4, v5.0.0, ..., v5.4.0].