ORA-01665: control file is not a standby control file

Users may see this error when trying to mount standby database after restore or during the switch over

SQL> ALTER DATABASE MOUNT STANDBY DATABASE;
ALTER DATABASE MOUNT STANDBY DATABASE
*
ERROR at line 1:
ORA-01665: control file is not a standby control file

SQL> SELECT database_role FROM v$database;
DATABASE_ROLE
----------------------------------------------------------------
PRIMARY

In current scenario, we see the database role as primary and trying to convert as Physical Standby. You can convert when database not mounted, otherwise you will see below error.

SQL> Alter database convert to physical standby;
Alter database convert to physical standby
*
ERROR at line 1:
ORA-01507: database not mounted

SQL> shutdown immediate
SQL> startup nomount;

SQL> Alter database convert to physical standby;
Database altered.
SQL> SELECT database_role FROM v$database;
DATABASE_ROLE
----------------------------------------------------------------
PHYSICAL STANDBY
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE disconnect from session;
Database altered.

Make sure you start the recovery using below command

sql> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE disconnect from session;

To avoid any user mistakes I would advise to use Data Guard broker

Refer below presentation related to Data Guard.

1. “Why Oracle DataGuard? New Features in Oracle 18c,19c”
https://www.oracleracexpert.com/2019/12/why-oracle-dataguard-new-features-in.html

2. Data Guard Physical Standby Setup in Oracle?
https://www.oracleracexpert.com/2019/02/webinar-data-guard-physical-standby.html

Regards
Satishbabu Gunukula, Oracle ACE
http://oracleracexpert.com