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 - Root composer.json requires vimeo/psalm ^5.20 -> satisfiable by vimeo/psalm[5.20.0, ..., 5.x-dev]. - phpunit/phpunit[11.2.0, ..., 11.3.x-dev] require phpunit/php-code-coverage ^11.0 -> satisfiable by phpunit/php-code-coverage[11.0.0, ..., 11.0.x-dev]. - phpunit/php-code-coverage[11.0.0, ..., 11.0.x-dev] require sebastian/complexity ^4.0 -> satisfiable by sebastian/complexity[4.0.0, 4.0.1, 4.0.x-dev]. - Conclusion: don't install sebastian/complexity 4.0.1 (conflict analysis result) - Root composer.json requires phpunit/phpunit ^11.2 -> satisfiable by phpunit/phpunit[11.2.0, ..., 11.3.x-dev].