Hi:
You are getting an expected error message. You can not replicate the database between interversion of ACS. In order to configure replication you should have same version of ACS. However, you can take backup o f your OLD ACSrunning 4.1 and restore the database simply on the ACSrunning version 4.2.
There is an exception added in ACS 4.2 where you can restore 4.1 database to 4.2
Restore from 4.1 backup file to ACS 4.2
You also need to check these options:
Check the User and Group Database
Cisco Secure ACS System Configuration
Restoring ACS backup file:
http://www.cisco.com/en/US/docs/net_mgmt/cisco_secure_access_control_server_for_windows/4.2/user/guide/SCBasic.html#wp222758
Regards,
JK
Do rate helpful posts-
~Jatin