S'assurer de la création de repository pour chaque entité du page bundle.
Verifier les annotation créer en ORM.

doctrine.yaml

    # IMPORTANT: You MUST configure your server version,
    # either here or in the DATABASE_URL env var (see .env file)
    #server_version: '13'

doctrine:
dbal:
url: '%env(resolve:DATABASE_URL)%'
orm:
auto_generate_proxy_classes: true
naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
auto_mapping: true
mappings:
App:
is_bundle: false
dir: '%kernel.project_dir%/src/Entity'
prefix: 'App\Entity'
alias: App

        SonataPageBundle: ~  

from sonata.