ORA-02291: integrity constraint (RMAN.RLH_F1) violated - parent key not found

 issue:

when I tried to register the oracle DB with catalog DB during registration process got the below error.

RMAN> REGISTER DATABASE;

database registered in recovery catalog

starting full resync of recovery catalog

got ORA-02291: integrity constraint (RMAN.RLH_F1) violated - parent key not found

ORA-06512: at "RMAN.DBMS_RCVCAT", line 7261 during resync

retrying with snapshot controlfile

Creating and using snapshot control file for resync

starting full resync of recovery catalog

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03008: error while performing automatic resync of recovery catalog

ORA-02291: integrity constraint (RMAN.RLH_F1) violated - parent key not found

Cause:

could be the same Db already registered and not properly unregistred ,so that we  got the above error.

Solution:

connect to RMAN catalog DB using Catalog user and  execute the below package.

Connected to:

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.11.0.0.0

SQL> select name,open_mode from v$database;

NAME      OPEN_MODE

--------- --------------------

4RMANCAT  READ WRITE

SQL> select 'EXEC DBMS_RCVCAT.UNREGISTERDATABASE('||DB_KEY||','||DBID||');'

  command, resetlogs_time

 from rc_database

 where name = '&db_name';  2    3    4

Enter value for db_name: TESTDB

old   4:  where name = '&db_name'

new   4:  where name = 'TESTDB'

 from rc_database

      *

ERROR at line 3:

ORA-00942: table or view does not exist

SQL> conn rman

Enter password:

Connected.

SQL> select 'EXEC DBMS_RCVCAT.UNREGISTERDATABASE('||DB_KEY||','||DBID||');'

  command, resetlogs_time

 from rc_database

 where name = '&db_name';  

Enter value for db_name: TESTDB

old   4:  where name = '&db_name'

new   4:  where name = 'TESTDB'

COMMAND

--------------------------------------------------------------------------------

RESETLOGS

---------

EXEC DBMS_RCVCAT.UNREGISTERDATABASE(85399,987618234);

28-JAN-21

SQL> EXEC DBMS_RCVCAT.UNREGISTERDATABASE(85399,987618234);

PL/SQL procedure successfully completed.

SQL> commit;

Commit complete.

SQL>

> rman target / catalog rman@RCATDB

Recovery Manager: Release 19.0.0.0.0 - Production on Wed Jan 12 06:11:50 2022

Version 19.6.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

connected to target database: TESTDB (DBID=987618234)

recovery catalog database Password:

connected to recovery catalog database

recovery catalog schema version 19.11.00.00. is newer than RMAN version

RMAN> REGISTER DATABASE ;

database registered in recovery catalog

starting full resync of recovery catalog

full resync complete

RMAN> list db_unique_name all;

List of Databases

DB Key  DB Name  DB ID            Database Role    Db_unique_name

------- ------- ----------------- ---------------  ------------------

86302   TESTDB    987618234        PRIMARY          TESTDB