LogicException：CSRF保护需要启用会话SF2

Question

我在symfony 2.4 Web应用程序中使用此命令行（php composer.phar update propel/propel-bundle）安装了propel并通过composer更新它。在更新我收到LogicException: CSRF protection needs sessions to be enabled SF2的捆绑包后，有人可以向我解释错误的原因并帮助我解决问题。

这里有关于我的composer.json文件的内容

"require": {
    "propel/propel-bundle": "1.2.*",
},

和我的config.yml

更新框架

framework:
    #esi:             ~
    #translator:      { fallback: "%locale%" }
    secret:          "%secret%"
    router:
        resource: "%kernel.root_dir%/config/routing.yml"
        strict_requirements: ~
    form:            ~
    csrf_protection: ~
    validation:      { enable_annotations: true }
    templating:
        engines: ['twig']
        #assets_version: SomeVersionScheme
    default_locale:  "%locale%"
    trusted_hosts:   ~# in app/config/config.yml
    session: ~
propel:
    path:       "%kernel.root_dir%/../vendor/propel"
    phing_path: "%kernel.root_dir%/../vendor/phing"
    session:
        # handler_id set to null will use default session handler from php.ini
        handler_id:  ~
    fragments:       ~
    http_method_override: true