Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires jackalope/jackalope-doctrine-dbal ^1.10 -> satisfiable by jackalope/jackalope-doctrine-dbal[1.10.0, 1.10.1, 1.x-dev]. - jackalope/jackalope-doctrine-dbal[1.10.0, ..., 1.x-dev] require jackalope/jackalope ^1.4.2 -> found jackalope/jackalope[1.4.2, ..., 1.x-dev] but it conflicts with your root composer.json require (dev-symfony-7 as 2.0). Problem 2 - jackalope/jackalope-doctrine-dbal[1.10.0, ..., 1.x-dev] require jackalope/jackalope ^1.4.2 -> found jackalope/jackalope[1.4.2, ..., 1.x-dev] but it conflicts with your root composer.json require (dev-symfony-7 as 2.0). - jackalope/jackalope dev-symfony-7 requires jackalope/jackalope-transport * -> satisfiable by jackalope/jackalope-doctrine-dbal[1.10.0, 1.10.1, 1.x-dev]. - Root composer.json requires jackalope/jackalope dev-symfony-7 as 2.0 -> satisfiable by jackalope/jackalope[dev-symfony-7].