Your requirements could not be resolved to an installable set of packages. Problem 1 - nette/tester v2.5.0 requires php >=8.0 <8.3 -> your php version (8.4.0-dev) does not satisfy that requirement. - nette/tester[v2.5.1, ..., v2.5.3] require php 8.0 - 8.3 -> your php version (8.4.0-dev) does not satisfy that requirement. - Root composer.json requires nette/tester ^2.5 -> satisfiable by nette/tester[v2.5.0, v2.5.1, v2.5.2, v2.5.3].