Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/saml2 ^6.1 -> satisfiable by simplesamlphp/saml2[v6.1.0]. - simplesamlphp/saml2 v6.1.0 requires simplesamlphp/assert ~2.0 -> found simplesamlphp/assert[v2.0.0] but it conflicts with your root composer.json require (^1.9). Problem 2 - Root composer.json requires simplesamlphp/xml-common ^2.7 -> satisfiable by simplesamlphp/xml-common[v2.7.0]. - simplesamlphp/xml-common v2.7.0 requires simplesamlphp/assert ~2.0 -> found simplesamlphp/assert[v2.0.0] but it conflicts with your root composer.json require (^1.9). Problem 3 - Root composer.json requires simplesamlphp/xml-security ^2.3 -> satisfiable by simplesamlphp/xml-security[v2.3.0]. - simplesamlphp/xml-security v2.3.0 requires simplesamlphp/assert ~2.0 -> found simplesamlphp/assert[v2.0.0] but it conflicts with your root composer.json require (^1.9). Problem 4 - Root composer.json requires simplesamlphp/simplesamlphp ^2.5@dev -> satisfiable by simplesamlphp/simplesamlphp[v2.5.0-rc3, v2.5.0-rc5]. - simplesamlphp/saml2 v6.1.0 requires simplesamlphp/assert ~2.0 -> found simplesamlphp/assert[v2.0.0] but it conflicts with your root composer.json require (^1.9). - simplesamlphp/simplesamlphp v2.5.0-rc3 requires simplesamlphp/saml2 ^5.1.0-rc1 -> found simplesamlphp/saml2[v5.1.0-rc1] but it does not match your minimum-stability. - simplesamlphp/simplesamlphp v2.5.0-rc5 requires simplesamlphp/saml2 ~6.0 -> satisfiable by simplesamlphp/saml2[v6.1.0].