Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires silverstripe/installer 5.4.x-dev -> satisfiable by silverstripe/installer[5.4.x-dev]. - silverstripe/installer 5.4.x-dev requires silverstripe/recipe-cms 5.4.x-dev -> satisfiable by silverstripe/recipe-cms[5.4.x-dev]. - silverstripe/recipe-cms 5.4.x-dev requires silverstripe/errorpage 2.4.x-dev -> found silverstripe/errorpage[2.4.0-beta1] but it does not match the constraint. See https://getcomposer.org/dep-on-root for details and assistance.