Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires lctrs/psalm-psr-container-plugin ^1.10 -> satisfiable by lctrs/psalm-psr-container-plugin[1.10.0]. - lctrs/psalm-psr-container-plugin 1.10.0 requires vimeo/psalm ^5.19.0 -> found vimeo/psalm[5.19.0, ..., 5.26.1] but it conflicts with your root composer.json require (^6.0.0). Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.