As https://github.com/BeSimple/BeSimpleSoap/commit/189dd1b4c7e87dec6cd35f58eacf5a7083f737a7 allows the use within Symfony 3.x but it's not included in any release yet. To use this package allongside a symfony 3, one must set the requirment to: "besimple/soap": "0.2.*@dev" while depending on a certain version number is considered more stable. By adding a version (tag in git) the dependency could become: "besimple/soap": "0.2.7"