Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/saml2 ~5.0.3 -> satisfiable by simplesamlphp/saml2[v5.0.3, v5.0.4]. - simplesamlphp/saml2[v5.0.3, ..., v5.0.4] require simplesamlphp/assert ~1.8.1 -> found simplesamlphp/assert[v1.8.1, v1.8.2] but it conflicts with your root composer.json require (~1.9.0). Problem 2 - Root composer.json requires simplesamlphp/simplesamlphp ~2.4.0 -> satisfiable by simplesamlphp/simplesamlphp[v2.4.0, v2.4.1, v2.4.2]. - simplesamlphp/saml2[v5.0.3, ..., v5.0.4] require simplesamlphp/assert ~1.8.1 -> found simplesamlphp/assert[v1.8.1, v1.8.2] but it conflicts with your root composer.json require (~1.9.0). - simplesamlphp/simplesamlphp[v2.4.0, ..., v2.4.2] require simplesamlphp/saml2 ^5.0.0 -> satisfiable by simplesamlphp/saml2[v5.0.3, v5.0.4].