Your requirements could not be resolved to an installable set of packages. Problem 1 - simplesamlphp/simplesamlphp dev-master requires simplesamlphp/saml2 v5.0.0-alpha.13 -> found simplesamlphp/saml2[v5.0.0-alpha.13] but it does not match your minimum-stability. - 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)].