ORA-02055: distributed update operation failed; rollback required

Problem

SQL> BEGIN
DBMS_REPCAT.ADD_MASTER_DATABASE (
gname => 'scott_repg',
master => 'repb',
use_existing_objects => TRUE,
copy_rows => TRUE,
propagation_mode => 'ASYNCHRONOUS');
END;
/
BEGIN
*
ERROR at line 1:
ORA-02055: distributed update operation failed; rollback required
ORA-00001: unique constraint (SYSTEM.REPCAT$_REPCAT_PRIMARY) violated
ORA-06512: at "SYS.DBMS_REPCAT_UTL", line 2649
ORA-06512: at "SYS.DBMS_REPCAT_RPC", line 313
ORA-06512: at "SYS.DBMS_REPCAT_MAS", line 223
ORA-06512: at "SYS.DBMS_REPCAT_MAS", line 2248
ORA-06512: at "SYS.DBMS_REPCAT", line 146
ORA-06512: at line 2

Solution :

1. Delete rows from SYSTEM.REPCAT$_REPCAT view.
2. Stop push job “dbms_defer_sys.push(destination=>’REPA’)”
3. “dbms_defer_sys.push(destination=>’REPB’)” else you will receive lock errors.
4. ReEnable the jobs when done.