Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires nucleos/user-bundle ^2.3 || ^3.4.0 -> satisfiable by nucleos/user-bundle[2.3.0, 3.4.0, ..., 3.6.1]. - nucleos/user-bundle 2.3.0 requires doctrine/persistence ^1.3 || ^2.1 || ^3.0 -> found doctrine/persistence[1.3.0, ..., 1.3.8, 2.1.0, ..., 2.5.7, 3.0.0, ..., 3.4.0] but it conflicts with your root composer.json require (^4.0.0). - nucleos/user-bundle[3.4.0, ..., 3.6.1] require doctrine/persistence ^2.3 || ^3.0 -> found doctrine/persistence[2.3.0, ..., 2.5.7, 3.0.0, ..., 3.4.0] but it conflicts with your root composer.json require (^4.0.0).