Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires tvdijen/ws-security, it could not be found in any version, there may be a typo in the package name. Problem 2 - 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, v2.1.3] 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)]. Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details. - It's a private package and you forgot to add a custom repository to find it Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.