Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires nettrine/fixtures ^0.8.0 -> satisfiable by nettrine/fixtures[0.8.x-dev (alias of dev-master)]. - nettrine/fixtures dev-master requires php >=8.2 -> your php version (8.1.31) does not satisfy that requirement. - nettrine/fixtures 0.8.x-dev is an alias of nettrine/fixtures dev-master and thus requires it to be installed too.