Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpspec/prophecy ^1.17 -> satisfiable by phpspec/prophecy[v1.17.0]. - phpspec/prophecy v1.17.0 requires php ^7.2 || 8.0.* || 8.1.* || 8.2.* -> your php version (8.3.0-dev) does not satisfy that requirement. Problem 2 - phpspec/prophecy-phpunit[v2.0.1, ..., v2.0.2] require phpspec/prophecy ^1.3 -> satisfiable by phpspec/prophecy[v1.17.0]. - phpspec/prophecy-phpunit v2.0.0 requires php ^7.3 -> your php version (8.3.0-dev) does not satisfy that requirement. - phpspec/prophecy v1.17.0 requires php ^7.2 || 8.0.* || 8.1.* || 8.2.* -> your php version (8.3.0-dev) does not satisfy that requirement. - Root composer.json requires phpspec/prophecy-phpunit ^2.0 -> satisfiable by phpspec/prophecy-phpunit[v2.0.0, v2.0.1, v2.0.2].