Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires laminas/laminas-cache-storage-adapter-test ^4.1 -> satisfiable by laminas/laminas-cache-storage-adapter-test[4.1.0]. - laminas/laminas-cache-storage-adapter-test 4.1.0 requires phpunit/phpunit ^10.5 -> found phpunit/phpunit[10.5.0, ..., 10.5.45] but it conflicts with your root composer.json require (^12.0.0). Problem 2 - Root composer.json requires phpunit/phpunit ^12.0.0 -> satisfiable by phpunit/phpunit[12.0.0, 12.0.1, 12.0.2]. - Root composer.json requires vimeo/psalm ^5.18 -> satisfiable by vimeo/psalm[5.18.0, ..., 5.26.1]. - phpunit/phpunit[12.0.0, ..., 12.0.2] require sebastian/diff ^7.0.0 -> satisfiable by sebastian/diff[7.0.0]. - Conclusion: don't install sebastian/diff 7.0.0 (conflict analysis result) Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.