[keycloak-user] Keycloak LDAP User Validation

Hello together, I have to following issue: I added LDAP/AD User federation to my keycloak server version 3.2.0.Final. So far so good everything is working I can import all the users and then can validate the users against the LDAP. But the target is that no user gets imported to keycloak. Thats working, too. Just switched off the import button. If I try to login now with my LDAP-credentials an error comes up. The error on the keycloak login page says: "Unexpected error when handling authentication request to identity provider". In the keycloak log it throws a "ReadOnlyException". But if I look into the sessions there is an active session with the user I tried to login. Did I miss any settings that keycloak can authenticate the user against LDAP/AD without importing all the users? Thank you for your help. Mit freundlichen Grüßen Felix Straub +49 7132 94 920297 Kaufland Informationssysteme GmbH & Co. KG Postfach 12 53 - 74172 Neckarsulm Kommanditgesellschaft Sitz: Neckarsulm Registergericht: Stuttgart HRA 104163