Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires php-stubs/wordpress-stubs 6.6.1 (exact version match: 6.6.1 or 6.6.1.0), found php-stubs/wordpress-stubs[dev-master, dev-foxy, dev-szepeviktor-patch-1, dev-szepeviktor-patch-2, v4.7.14, ..., v4.9.20, v5.0, ..., v5.9.9, v6.0.0, ..., v6.6.0] but it does not match the constraint. Problem 2 - php-stubs/wp-cli-stubs is locked to version v2.10.0 and an update of this package was not requested. - php-stubs/wp-cli-stubs v2.10.0 requires php-stubs/wordpress-stubs ^4.7 || ^5.0 || ^6.0 -> found php-stubs/wordpress-stubs[v4.7.14, ..., v4.9.20, v5.0, ..., v5.9.9, v6.0.0, ..., v6.6.0] but it conflicts with your root composer.json require (6.6.1). Problem 3 - szepeviktor/phpstan-wordpress is locked to version v1.3.5 and an update of this package was not requested. - szepeviktor/phpstan-wordpress v1.3.5 requires php-stubs/wordpress-stubs ^4.7 || ^5.0 || ^6.0 -> found php-stubs/wordpress-stubs[v4.7.14, ..., v4.9.20, v5.0, ..., v5.9.9, v6.0.0, ..., v6.6.0] but it conflicts with your root composer.json require (6.6.1). Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.