Your requirements could not be resolved to an installable set of packages. Problem 1 - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.3.12) does not satisfy that requirement. - php-mock/php-mock-phpunit 2.9.0 requires phpunit/phpunit ^6 || ^7 || ^8 || ^9 || ^10.0.17 -> found phpunit/phpunit[6.0.0, ..., 6.5.14, 7.0.0, ..., 7.5.20, 8.0.0, ..., 8.5.40, 9.0.0, ..., 9.6.21, 10.0.17, ..., 10.5.38] but it conflicts with your root composer.json require (^11.0.0). - Root composer.json requires php-mock/php-mock-phpunit ^2.9.0 -> satisfiable by php-mock/php-mock-phpunit[2.9.0, 2.10.0]. - vimeo/psalm[5.20.0, ..., 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]. - phpunit/php-code-coverage 11.0.7 requires nikic/php-parser ^5.3.1 -> satisfiable by nikic/php-parser[v5.3.1]. - 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]. - phpunit/phpunit[11.4.2, ..., 11.4.3] require phpunit/php-code-coverage ^11.0.7 -> satisfiable by phpunit/php-code-coverage[11.0.7]. - phpunit/phpunit[11.4.2, ..., 11.4.3] require sebastian/diff ^6.0.2 -> satisfiable by sebastian/diff[6.0.2]. - php-mock/php-mock-phpunit 2.10.0 requires phpunit/phpunit ^6 || ^7 || ^8 || ^9 || ^10.0.17 || ^11 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.4.3]. - Conclusion: don't install phpunit/phpunit 11.3.6 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.3.5 (conflict analysis result) - Conclusion: don't install vimeo/psalm 5.19.1 (conflict analysis result) - Conclusion: don't install vimeo/psalm[5.17.0] | install one of nikic/php-parser[v4.16.0, v4.17.1, v4.19.0] (conflict analysis result) - Conclusion: don't install vimeo/psalm[5.18.0] | install one of nikic/php-parser[v4.16.0, v4.17.1, v4.19.0] (conflict analysis result) - Conclusion: don't install vimeo/psalm[5.19.0] | install one of nikic/php-parser[v4.16.0, v4.17.1, v4.19.0] (conflict analysis result) - Conclusion: don't install nikic/php-parser v4.19.0 (conflict analysis result) - Conclusion: don't install nikic/php-parser v4.17.1 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.3.2 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.3.1 (conflict analysis result) - Conclusion: don't install nikic/php-parser v4.16.0 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.2.7 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.2.3 (conflict analysis result) - Conclusion: don't install phpunit/phpunit 11.0.0 (conflict analysis result) - Root composer.json requires psalm/plugin-phpunit ^0.18.4 -> satisfiable by psalm/plugin-phpunit[0.18.4]. - Root composer.json requires vimeo/psalm ^5.17.0 -> satisfiable by vimeo/psalm[5.17.0, ..., 5.26.1]. - Conclusion: don't install nikic/php-parser[v5.3.1] | install one of vimeo/psalm[5.17.0, ..., 5.21.1] (conflict analysis result) Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.