Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/simplesamlphp ^3@dev -> satisfiable by simplesamlphp/simplesamlphp[3.0.x-dev (alias of dev-master)]. - simplesamlphp/simplesamlphp dev-master requires symfony/http-foundation ~7.3.0 -> found symfony/http-foundation[v7.3.0, v7.3.1, v7.3.2, v7.3.3] but it conflicts with your root composer.json require (^6.4). - simplesamlphp/simplesamlphp 3.0.x-dev is an alias of simplesamlphp/simplesamlphp dev-master and thus requires it to be installed too.