Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires silverstripe/installer 6.0.x-dev -> satisfiable by silverstripe/installer[6.0.x-dev]. - silverstripe/installer 6.0.x-dev requires silverstripe/vendor-plugin 3.0.x-dev -> found silverstripe/vendor-plugin[3.0.x-dev] but it conflicts with your root composer.json require (^2).