Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires yiisoft/yii-testing dev-master -> satisfiable by yiisoft/yii-testing[dev-master]. - yiisoft/yii-testing dev-master requires phpunit/phpunit ^9.5 -> found phpunit/phpunit[9.5.0, ..., 9.6.x-dev] but it conflicts with your root composer.json require (^11.2). Problem 2 - phpunit/phpunit[11.2.0, ..., 11.3.x-dev] require php >=8.2 -> your php version (8.1.29) does not satisfy that requirement. - Root composer.json requires phpunit/phpunit ^11.2 -> satisfiable by phpunit/phpunit[11.2.0, ..., 11.3.x-dev].