error while integrating FOSUserBundle with FOSOAuthServer

I am trying to integrate FOSUserBundle with FOSOAuthServerBundle to proect my RESTFul APIs but i am getting following error while accessing login page , i am quite new to it so i dont know how to get rid off this error.

here i am trying to open a login form of FOSUserBundle so that i can login into it and get the Token

here is my security.yml

# FOR FOSUserBundle 

security:

    providers:
        fos_userbundle:
            id: fos_user.user_provider.username

    encoders:
        "FOS\UserBundle\Model\UserInterface": sha512

    firewalls:
        main:
            pattern: ^/
            form_login:
                provider: fos_userbundle
                csrf_provider: form.csrf_provider
            logout:       true
            anonymous:    true

    access_control:
        - { path: ^/login, role: IS_AUTHENTICATED_ANONYMOUSLY }
        - { path: ^/register, role: IS_AUTHENTICATED_ANONYMOUSLY }
        - { path: ^/resetting, role: IS_AUTHENTICATED_ANONYMOUSLY }
        - { path: ^/admin/, role: ROLE_ADMIN }

    role_hierarchy:
        ROLE_ADMIN:       ROLE_USER
        ROLE_SUPER_ADMIN: ROLE_ADMIN


# FOR FOSOAuthServerBundle 

security:
    providers:
        fos_userbundle:
            id: fos_user.user_provider.username
    firewalls:
        oauth_token:
            pattern:    ^/oauth/v2/token
            security:   false


        oauth_authorize:
            pattern:    ^/oauth/v2/auth
            form_login:
                 provider: fos_userbundle
                 check_path: /oauth/v2/auth/login_check
                 login_path: /oauth/v2/auth/login
            anonymous: true
            # Add your favorite authentication process here

        api:
            pattern:    ^/api
            fos_oauth:  true
            stateless:  true
            anonymous: true # can be omitted as its default value

    access_control:
           - { path: ^/api, roles: [ IS_AUTHENTICATED_FULLY ] }