Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires doctrine/mongodb-odm 2.4 -> satisfiable by doctrine/mongodb-odm[2.4.0]. - doctrine/orm[3.0.0-beta1, ..., 3.0.x-dev] require doctrine/collections ^2.1 -> satisfiable by doctrine/collections[2.1.0, ..., 2.1.x-dev]. - Conclusion: don't install doctrine/collections 2.1.4 (conflict analysis result) - Root composer.json requires doctrine/orm ^3.0 -> satisfiable by doctrine/orm[3.0.0-beta1, 3.0.0-beta2, 3.0.x-dev].