Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpspec/prophecy-phpunit ^2.0.2 -> satisfiable by phpspec/prophecy-phpunit[v2.0.2]. - phpspec/prophecy-phpunit v2.0.2 requires phpunit/phpunit ^9.1 -> found phpunit/phpunit[9.1.0, ..., 9.6.15] but it conflicts with your root composer.json require (^10.0.0). Problem 2 - Root composer.json requires phpspec/prophecy ^1.17.0 -> satisfiable by phpspec/prophecy[v1.17.0]. - phpunit/phpunit[10.0.0, ..., 10.5.1] require sebastian/recursion-context ^5.0 -> satisfiable by sebastian/recursion-context[5.0.0]. - Conclusion: don't install sebastian/recursion-context 5.0.0 (conflict analysis result) - Root composer.json requires phpunit/phpunit ^10.0.0 -> satisfiable by phpunit/phpunit[10.0.0, ..., 10.5.1]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.