Your requirements could not be resolved to an installable set of packages. Problem 1 - simplesamlphp/simplesamlphp dev-master requires simplesamlphp/simplesamlphp-module-adfs ^2.1 -> satisfiable by simplesamlphp/simplesamlphp-module-adfs[v2.1.0, v2.1.1, v2.1.2] from composer repo (https://repo.packagist.org) but simplesamlphp/simplesamlphp-module-adfs is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance. - simplesamlphp/simplesamlphp 3.0.x-dev is an alias of simplesamlphp/simplesamlphp dev-master and thus requires it to be installed too. - Root composer.json requires simplesamlphp/simplesamlphp ^3@dev -> satisfiable by simplesamlphp/simplesamlphp[3.0.x-dev (alias of dev-master)].