Sulu 2.5 upgrade: Tree listener was not found on your entity manager, it must be hooked into the event manager

Question

I'm trying to upgrade our sulu from 2.4 to 2.5, but are running into this issue:

Gedmo\Exception\InvalidMappingException:
Tree listener was not found on your entity manager, it must be hooked into the event manager

  at sulu/vendor/gedmo/doctrine-extensions/src/Tree/Entity/Repository/AbstractTreeRepository.php:56
  at Gedmo\Tree\Entity\Repository\AbstractTreeRepository->__construct(object(EntityManagerGhostEbeb667), object(ClassMetadata))
     (sulu/vendor/doctrine/doctrine-bundle/Repository/ContainerRepositoryFactory.php:93)
  at Doctrine\Bundle\DoctrineBundle\Repository\ContainerRepositoryFactory->getOrCreateRepository(object(EntityManagerGhostEbeb667), object(ClassMetadata))
     (sulu/vendor/doctrine/doctrine-bundle/Repository/ContainerRepositoryFactory.php:70)
  at Doctrine\Bundle\DoctrineBundle\Repository\ContainerRepositoryFactory->getRepository(object(EntityManagerGhostEbeb667), 'SuluMediaBundle:Collection')
     (sulu/vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php:825)
  at Doctrine\ORM\EntityManager->getRepository('SuluMediaBundle:Collection')
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:2391)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::getSuluMedia_CollectionRepositoryService(object(App_KernelDevDebugContainer))
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:2534)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::getSuluMedia_MediaManagerService(object(App_KernelDevDebugContainer))
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:4515)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::getSuluMarkup_LinkTag_ProviderPoolService(object(App_KernelDevDebugContainer))
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:4531)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::getSuluMarkup_ParserService(object(App_KernelDevDebugContainer))
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:4547)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::getSuluMarkup_ResponseListenerService(object(App_KernelDevDebugContainer))
     (sulu/var/cache/admin/dev/ContainerXXZPsXp/App_KernelDevDebugContainer.php:1549)
  at ContainerXXZPsXp\App_KernelDevDebugContainer::ContainerXXZPsXp\{closure}()
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:257)
  at Symfony\Component\EventDispatcher\EventDispatcher::Symfony\Component\EventDispatcher\{closure}(object(ResponseEvent), 'kernel.response', object(EventDispatcher))
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:220)
  at Symfony\Component\EventDispatcher\EventDispatcher->callListeners(array(object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure), object(Closure)), 'kernel.response', object(ResponseEvent))
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:56)
  at Symfony\Component\EventDispatcher\EventDispatcher->dispatch(object(ResponseEvent), 'kernel.response')
     (sulu/vendor/symfony/http-kernel/HttpKernel.php:215)
  at Symfony\Component\HttpKernel\HttpKernel->filterResponse(object(Response), object(Request), 2)
     (sulu/vendor/symfony/http-kernel/HttpKernel.php:203)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 2)
     (sulu/vendor/symfony/http-kernel/HttpKernel.php:76)
  at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 2, false)
     (sulu/vendor/symfony/http-kernel/EventListener/ErrorListener.php:108)
  at Symfony\Component\HttpKernel\EventListener\ErrorListener->onKernelException(object(ExceptionEvent), 'kernel.exception', object(EventDispatcher))
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:260)
  at Symfony\Component\EventDispatcher\EventDispatcher::Symfony\Component\EventDispatcher\{closure}(object(ExceptionEvent), 'kernel.exception', object(EventDispatcher))
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:220)
  at Symfony\Component\EventDispatcher\EventDispatcher->callListeners(array(object(Closure), object(Closure), object(Closure), object(Closure), object(Closure)), 'kernel.exception', object(ExceptionEvent))
     (sulu/vendor/symfony/event-dispatcher/EventDispatcher.php:56)
  at Symfony\Component\EventDispatcher\EventDispatcher->dispatch(object(ExceptionEvent), 'kernel.exception')
     (sulu/vendor/symfony/http-kernel/HttpKernel.php:240)
  at Symfony\Component\HttpKernel\HttpKernel->handleThrowable(object(InvalidMappingException), object(Request), 1)
     (sulu/vendor/symfony/http-kernel/HttpKernel.php:133)
  at Symfony\Component\HttpKernel\HttpKernel->terminateWithException(object(InvalidMappingException), object(Request))
     (sulu/vendor/symfony/http-kernel/EventListener/DebugHandlersListener.php:74)
  at Symfony\Component\HttpKernel\EventListener\DebugHandlersListener::Symfony\Component\HttpKernel\EventListener\{closure}(object(InvalidMappingException))
     (sulu/vendor/symfony/error-handler/ErrorHandler.php:537)
  at Symfony\Component\ErrorHandler\ErrorHandler->handleException(object(InvalidMappingException))

I did follow the upgrade.md, but can not even identify the origin of the error. I suspect the services.yml but would be greatfull for any suggestion on how to solve this.