kunstmaan/admin-bundle

config/packages/kunstmaan_admin.yaml

kunstmaan_admin:
    multi_language: true
    required_locales: nl|fr|en
    default_locale: en
    admin_locales: ['en']
    website_title: 'MyProject' #Rename this to your website name
    exception_logging: false
    authentication:
        enable_new_authentication: true

config/routes/kunstmaan_admin.yaml

KunstmaanAdminBundle:
    resource: "@KunstmaanAdminBundle/Resources/config/routing.yml"
    # If your site is not multi language, remove the "{_locale}/" part of prefix and requirements
    prefix:   /{_locale}/
    requirements:
        _locale: "%kunstmaan_admin.required_locales%"