Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires boesing/psalm-plugin-stringf ^1.4 -> satisfiable by boesing/psalm-plugin-stringf[1.4.0]. - boesing/psalm-plugin-stringf 1.4.0 requires vimeo/psalm ^4.30 || ^5.0 -> found vimeo/psalm[4.30.0, 5.0.0, ..., 5.26.1] but it conflicts with your root composer.json require (^6.0.0). Problem 2 - lctrs/psalm-psr-container-plugin 1.9.0 requires vimeo/psalm ^5.0.0 -> found vimeo/psalm[5.0.0, ..., 5.26.1] but it conflicts with your root composer.json require (^6.0.0). - 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). - Root composer.json requires lctrs/psalm-psr-container-plugin ^1.9 -> satisfiable by lctrs/psalm-psr-container-plugin[1.9.0, 1.10.0]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.