Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/simplesamlphp ~2.5@dev -> satisfiable by simplesamlphp/simplesamlphp[v2.5.0-rc3, v2.5.0-rc5]. - simplesamlphp/simplesamlphp v2.5.0-rc3 requires simplesamlphp/assert ^1.9 -> found simplesamlphp/assert[v1.9.0, v1.9.1] but it conflicts with your root composer.json require (~2.0). - simplesamlphp/simplesamlphp v2.5.0-rc5 requires simplesamlphp/assert ~1.9 -> found simplesamlphp/assert[v1.9.0, v1.9.1] but it conflicts with your root composer.json require (~2.0).