Open Stack

Hi All,
openstack version: Stain
keycloak   version: 8.0.0

I have configured keystone+horizon to use SSO (Keycloak). In Keycloak 
database there are two sorts of users:
1. Those who have attribute "domain" which is mapped into openstack's 
domain
2. Those who do not have this attribute

If Keycloak's user without attribute "domian" or it is a non-existent 
user in keystone, is successfully authenticated (in Keycloak) then 
keystone returns json:

{u'error': {u'message': u'The request you have made requires 
authentication.', u'code': 401, u'title': u'Unauthorized'}}


How to configure keystone to return more user friendly error page 
(custom one)?
If it's possible, then what about other services which they parse this 
reponse?


Regards,
Pawel