symfony - Authentication request could not be processed -

i implementing login module i'm trying use database user entity authentication.

i have configured security.yml file follows integrate user entity:

providers:     our_db_provider:         entity:            class: userbundle:user            property: username 

but facing error:

authentication request not processed due system problem.

can let me know why issue coming?

if use class authentication inherit userbundle\entity\user, have specify latter superclass instead of entity. here example user.orm.yaml :

userbundle\entity\user: type: mappedsuperclass [...] 

more info on doctrine documentation : http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/inheritance-mapping.html