OMS 12.1.0.4 installation failed with "The database details which you have provided doesn't contain valid Management Repository. Provide correct database details and retry"

Yesterday I was installing OMS 121.0.4 and got below error while attempting to connect to database:-

OMS 12.1.0.4 installation failed with "The database details which you have provided doesn't contain valid Management Repository. Provide correct database details and retry"

Cause :-

Generally this error comes when the database we are using as OMS database was already used as a database for OMS installation before or A failed OMS installation already happened using this database.

Solution :-

we have to properly clean the database before using it again as a OMS database :-

Below steps I did to clean my database :-

1. Drop sysman related schemas.

DROP USER SYSMAN CASCADE;  ( will take time)
DROP USER SYSMAN_OPSS CASCADE;
DROP USER SYSMAN_MDS CASCADE;
DROP USER SYSMAN_APM CASCADE;
DROP USER SYSMAN_RO CASCADE;

2. Remove Synonyms related to sysman accounts :-

DECLARE
  CURSOR l_syn_csr IS
    SELECT 'DROP ' ||
      CASE owner
        WHEN 'PUBLIC'
          THEN 'PUBLIC SYNONYM '
        ELSE 'SYNONYM ' || owner || '.'
      END ||
      synonym_name AS cmd
    FROM
      dba_synonyms 
    WHERE
      table_owner IN (
        'SYSMAN',
        'SYSMAN_MDS',
        'MGMT_VIEW',
        'SYSMAN_BIP',
        'SYSMAN_APM',
        'BIP',
        'SYSMAN_OPSS',
        'SYSMAN_RO'
      );
BEGIN
  FOR l_syn_rec IN l_syn_csr LOOP
    BEGIN
      EXECUTE IMMEDIATE l_syn_rec.cmd;
    EXCEPTION
      WHEN OTHERS THEN
        dbms_output.put_line( '===> ' || l_syn_rec.cmd );
        dbms_output.put_line( sqlerrm );
    END;
  END LOOP;
END;
/

3. Removing remaining Objects and tablespaces :-

DROP USER mgmt_view CASCADE;
DROP TABLESPACE mgmt_ecm_depot_ts INCLUDING CONTENTS AND DATAFILES CASCADE CONSTRAINTS;
DROP TABLESPACE mgmt_tablespace   INCLUDING CONTENTS AND DATAFILES CASCADE CONSTRAINTS;
DROP TABLESPACE mgmt_ad4j_ts      INCLUDING CONTENTS AND DATAFILES CASCADE CONSTRAINTS;

4.  As proper database cleaning using RepManager dropall didn't happen, so we have to clean up the registry details :-

DELETE
  FROM
    schema_version_registry
  WHERE
    (comp_name,owner) IN (
      ('Authorization Policy Manager','SYSMAN_APM'),
      ('Metadata Services','SYSMAN_MDS'),
      ('Oracle Platform Security Services','SYSMAN_OPSS')
    );
commit;

5. Now the database clean up completed, Please continue with the installation, I tried and it completed successfully.

I hope this article helped you, Please go through the below article also for proper error details :-
https://sites.google.com/site/yetanotherocm/home/system-builds/cronulla/07-complete-oms-12-1-0-3-1-installation

Thanks
Amit Rath