Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires sulu/sulu dev-feature/symfony-7-support as 2.6.3, found sulu/sulu[dev-enhancement/phpunit-data-providers, 0.1.0, ..., 0.18.2, 1.0.0-RC1, ..., 1.6.x-dev, 2.0.0-alpha1, ..., 2.6.x-dev, 3.0.x-dev] but it does not match the constraint.