[keycloak-user] Google login without automatic user registration

[Scott Thibault]

Out-of-the-box, the First Broker Login flow automatically registers
non-existing users authenticated by an identity provider.  I would not like
anyone with a valid Google account to be able to login, but only those with
existing accounts.  However, any attempt to create a custom flow without
the "Create User If Unique" item leads to an error=invalid_user_credentials.

Is there some solution that would allow me to prevent users without an
existing account to login via the Google identity provider?