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, v1.18.0, v1.19.0]. - phpspec/prophecy v1.17.0 requires php ^7.2 || 8.0.* || 8.1.* || 8.2.* -> your php version (8.4.0-dev) does not satisfy that requirement. - phpspec/prophecy[v1.18.0, ..., v1.19.0] require php ^7.2 || 8.0.* || 8.1.* || 8.2.* || 8.3.* -> your php version (8.4.0-dev) does not satisfy that requirement.