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, ..., 10.5.35] but it conflicts with your root composer.json require (^11.0). Problem 2 - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.3.9) does not satisfy that requirement. - Root composer.json requires psalm/plugin-phpunit ^0.19.0 -> satisfiable by psalm/plugin-phpunit[0.19.0]. - Conclusion: don't install nikic/php-parser[v4.17.0] | install one of vimeo/psalm[5.18.0, 5.19.0] (conflict analysis result) - vimeo/psalm[5.19.0, ..., 5.21.1] require sebastian/diff ^4.0 || ^5.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1]. - You can only install one version of a package, so only one of these can be installed: sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1, 6.0.0, 6.0.1, 6.0.2]. - Conclusion: don't install one of sebastian/diff[6.0.2], vimeo/psalm[5.18.0] (conflict analysis result) - Conclusion: install sebastian/diff 6.0.2 (conflict analysis result) - Root composer.json requires vimeo/psalm ^5.18 -> satisfiable by vimeo/psalm[5.18.0, ..., 5.26.1]. - Root composer.json requires phpunit/phpunit ^11.0 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.3.6]. - psalm/plugin-phpunit 0.19.0 requires vimeo/psalm dev-master || ^5@beta || ^5.0 -> satisfiable by vimeo/psalm[5.18.0, ..., 5.26.1]. - vimeo/psalm[5.26.0, ..., 5.26.1] require nikic/php-parser ^4.17 -> satisfiable by nikic/php-parser[v4.17.0, ..., v4.19.4]. - vimeo/psalm[5.22.0, ..., 5.25.0] require nikic/php-parser ^4.16 -> satisfiable by nikic/php-parser[v4.16.0, ..., v4.19.4]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.0.0, ..., v4.19.4, v5.0.0, ..., v5.3.0]. - Conclusion: install nikic/php-parser v5.1.0 (conflict analysis result) Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.