php__symfony__book/config/packages/framework.yaml

framework:
    secret: '%env(APP_SECRET)%'
    #default_locale: en
    #csrf_protection: ~
    #http_method_override: true

    # uncomment this entire section to enable sessions
    session:
        # With this config, PHP's native session handling is used
        handler_id: ~

    #esi: ~
    #fragments: ~
    php_errors:
        log: true