Symfony2.1: The CSRF token is invalid. Only in browser, PHPUnit WebTestCase works without error

Question

How can I debug why in all my browsers I got The CSRF token is invalid error, but when I test same form with Functional test it works?

Answer 1

When I commented my config.yml as below, everything started working? so new question is: What is wrong with commented part of this configuration?

session:
    auto_start:     true
    # cookie_lifetime:   86400
    # cookie_path:       \
    # cookie_domain:     example.com
    # cookie_secure:     true
    # cookie_httponly:   true