Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/simplesamlphp ^2.6, found simplesamlphp/simplesamlphp[dev-feature/http-client, ..., dev-bugfix/path_translated, v1.12.0, ..., 1.19.9, v2.0.0-beta.1, ..., v2.5.0-rc5, 3.0.x-dev (alias of dev-master)] but it does not match the constraint.