Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^10.5 -> satisfiable by phpunit/phpunit[10.5.0, ..., 10.5.16]. - phpunit/phpunit[10.5.0, ..., 10.5.16] require php >=8.1 -> your php version (8.0.30) does not satisfy that requirement. Problem 2 - php-mock/php-mock-phpunit 2.10.0 requires phpunit/phpunit ^6 || ^7 || ^8 || ^9 || ^10.0.17 || ^11 -> satisfiable by phpunit/phpunit[10.5.0, ..., 10.5.16]. - php-mock/php-mock-phpunit[2.7.1, ..., 2.9.0] require phpunit/phpunit ^6 || ^7 || ^8 || ^9 || ^10.0.17 -> satisfiable by phpunit/phpunit[10.5.0, ..., 10.5.16]. - php-mock/php-mock-phpunit 2.7.0 requires phpunit/phpunit ^6 || ^7 || ^8 || ^9 || ^10 -> satisfiable by phpunit/phpunit[10.5.0, ..., 10.5.16]. - php-mock/php-mock-phpunit[2.6.0, ..., 2.6.1] require phpunit/phpunit ^6 || ^7 || ^8 || ^9 -> found phpunit/phpunit[6.0.0, ..., 6.5.14, 7.0.0, ..., 7.5.20, 8.0.0, ..., 8.5.37, 9.0.0, ..., 9.6.18] but it conflicts with your root composer.json require (^10.5). - phpunit/phpunit[10.5.0, ..., 10.5.16] require php >=8.1 -> your php version (8.0.30) does not satisfy that requirement. - Root composer.json requires php-mock/php-mock-phpunit ^2.6 -> satisfiable by php-mock/php-mock-phpunit[2.6.0, ..., 2.10.0].