Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/simplesamlphp ^2.5 -> satisfiable by simplesamlphp/simplesamlphp[v2.5.0, v2.5.1, v2.5.2]. - simplesamlphp/simplesamlphp[v2.5.0, ..., v2.5.2] require simplesamlphp/saml2 ~6.1 -> satisfiable by simplesamlphp/saml2[dev-master, v6.1.0, ..., v6.2.1] from composer repo (https://repo.packagist.org) but simplesamlphp/saml2 dev-release-7.x is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance.