FriendsOfSymfony/FOSUserBundle — Issue #535: Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken::serialize() must return a string or NULL 
Author: Raulken
Created: 2012-02-16 18:41:28+00:00
State: open

this error return to me when i make normal login

but only now,(after installing FOSFacebookBundle), before i can login normally
someone know why return this error?

you want read some file(config.yml,security.yml) ?

thx