Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires doctrine/common ^3.0 -> satisfiable by doctrine/common[3.0.0, ..., 3.4.5]. - doctrine/common[3.0.0, ..., 3.2.2] require doctrine/persistence ^2.0 -> found doctrine/persistence[2.0.0, ..., 2.5.7] but it conflicts with your root composer.json require (^4.0). - doctrine/common[3.3.0, ..., 3.4.5] require doctrine/persistence ^2.0 || ^3.0 -> found doctrine/persistence[2.0.0, ..., 2.5.7, 3.0.0, ..., 3.4.0] but it conflicts with your root composer.json require (^4.0).