Your requirements could not be resolved to an installable set of packages. Problem 1 - phpspec/prophecy v1.15.0 requires php ^7.2 || ~8.0, <8.2 -> your php version (8.3.0RC3) does not satisfy that requirement. - phpspec/prophecy[v1.16.0, ..., v1.17.0] require php ^7.2 || 8.0.* || 8.1.* || 8.2.* -> your php version (8.3.0RC3) does not satisfy that requirement. - Root composer.json requires phpspec/prophecy ^1.15.0 -> satisfiable by phpspec/prophecy[v1.15.0, v1.16.0, v1.17.0].