Your requirements could not be resolved to an installable set of packages. Problem 1 - vimeo/psalm[5.24.0, ..., 5.25.0] require nikic/php-parser ^4.16 -> found nikic/php-parser[v4.16.0, ..., v4.19.1] but it conflicts with your root composer.json require (^5.1.0). - Root composer.json requires vimeo/psalm ^5.24.0 -> satisfiable by vimeo/psalm[5.24.0, 5.25.0]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.