Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires silverstripe/installer 5.0.x-dev -> satisfiable by silverstripe/installer[5.0.x-dev]. - silverstripe/installer 5.0.x-dev requires silverstripe/recipe-cms 5.0.x-dev -> found silverstripe/recipe-cms[5.0.x-dev] but it conflicts with your root composer.json require (^4.4). Problem 2 - symbiote/silverstripe-gridfieldextensions[3.2.0, ..., 3.x-dev] require silverstripe/vendor-plugin ^1.0 -> found silverstripe/vendor-plugin[1.0.0, ..., 1.x-dev] but it conflicts with your root composer.json require (^2). - Root composer.json requires symbiote/silverstripe-gridfieldextensions ^3.2 -> satisfiable by symbiote/silverstripe-gridfieldextensions[3.2.0, ..., 3.x-dev].