You must configure the check path to be handled by the firewall using form_login in your security firewall configuration

I think you need to put form_login under a firewall ( either main or add another one )

form_login under main firewall :

firewalls:               main:    pattern: ^/admin    form_login:        provider:               fos_userbundle        login_path:             fos_user_security_login         check_path:             fos_user_security_check        csrf_provider:          form.csrf_provider        logout:       true        anonymous:    true ....

form_login under another firewall

firewalls:                   main:        pattern: ^/admin    second_firewall:        pattern: ^/        form_login:            provider:               fos_userbundle            login_path:             fos_user_security_login             check_path:             fos_user_security_check            csrf_provider:          form.csrf_provider            logout:       true            anonymous:    true .....

Your code is wrong only in the part of check_path value.

This is your original code:

firewalls:                   main:        pattern: ^/admin        form_login:            provider:               fos_userbundle            login_path:             fos_user_security_login             check_path:             fos_user_security_check            csrf_provider:          form.csrf_provider            logout:       true            anonymous:    true

And you should use something like:

firewalls:                   main:        pattern: ^/admin        form_login:            provider:               fos_userbundle            login_path:             fos_user_security_login             check_path:             /login_check            csrf_provider:          form.csrf_provider            logout:       true            anonymous:    true

Note that check_path has as value only a string. If you use the value fos_user_security_check you are calling to SecurityController.php class and invoking the checkAction() method which exactly only throws an RuntimeError Exception with the error displayed "You must configure the check path to be handled by the firewall using form_login in your security firewall configuration.". So the fix is so simple that not use the value fos_user_security_check

pattern: ^/admin

This is possibly where your problems start.

Try changing this back to ^/

Then change your routes for FosUserBundle

# app/config/routing.ymlfos_user_security:    resource: "@FOSUserBundle/Resources/config/routing/security.xml"    prefix: /adminfos_user_profile:    resource: "@FOSUserBundle/Resources/config/routing/profile.xml"    prefix: /admin/profilefos_user_register:    resource: "@FOSUserBundle/Resources/config/routing/registration.xml"    prefix: /admin/registerfos_user_resetting:    resource: "@FOSUserBundle/Resources/config/routing/resetting.xml"    prefix: /admin/resettingfos_user_change_password:    resource: "@FOSUserBundle/Resources/config/routing/change_password.xml"    prefix: /admin/profile