Hi all. As a demand from some client, we have to implement the Oracle backend, with idea of using an existing schema for authenticating users using some mfa tool that only supports ldap. I began for last version at this date (2.6.1), but have this error: 6241cb6b backsql_oc_get_attr_mapping(): error executing at_query "SELECT name,sel_expr,from_tbls,join_where,add_proc,delete_proc,param_order,expect_return,sel_expr_u FROM ldap_attr_mappings WHERE oc_map_id=?" for objectClass "organization" with param oc_id=3 6241cb6b Return code: -1 6241cb6b <==backsql_load_schema_map() In order for doing some debugging, I changed slapd and unixodbc to point to an mysql, and works fine. So I found some entry on internet from a person who had it working on some version, but when changing it does not work. Also, I monitored with sys user last queries on v$sql. and last query that reached DB was , so it appears that error occurs at preparing the attribute mapping query, and code breaks before sending the query. I found another entry about this, where someone told that he have it working on version 2.3.24 and he could not make it work on other version. So I begin installing several OpenLDAP versions since mentioned one, and from there to version 2.3.24 I found that Oracle backend is working fine. Beginning 2.4.24, and onwards versions, it starts to show mentioned error. I tried both on my Mint 20.3 personal machine, and with client's server which is a CentOS 7.8. For tests, I used same Oracle DB instance. Only copy the slapd.conf from working OpenLDAP/Oracle to the version I tested.