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

    templating:
        engines: ['twig']

    cache:
        app: cache.adapter.redis
        default_redis_provider: "redis://%env(REDIS_HOST)%"

    session:
        handler_id: ~
        cookie_secure: auto
        cookie_samesite: lax
        save_path: "%kernel.project_dir%/var/sessions/%kernel.environment%"

    assets:
        base_url: '%env(APP_ASSET_URL)%'
        packages:
            asset: ~

    esi: true
    fragments: ~
    php_errors:
        log: true
framework:
    secret: '%env(APP_SECRET)%'
    default_locale: fr
    #csrf_protection: ~
    #http_method_override: true

    templating:
        engines: ['twig']

    cache:
        app: cache.adapter.redis
        default_redis_provider: "redis://%env(REDIS_HOST)%"

    session:
        handler_id: 'session.handler.native_file'
        cookie_secure: auto
        cookie_samesite: lax
        save_path: "%kernel.project_dir%/var/sessions/%kernel.environment%"

    assets:
        base_url: '%env(APP_ASSET_URL)%'
        packages:
            asset: ~

    esi: true
    fragments: ~
    php_errors:
        log: true

Save session into dedicated folder
Save session into dedicated folder
