ORA-01155: the database is being opened, closed, mounted or dismounted

I got ” ORA-01155: the database is being opened, closed, mounted or dismounted ”  error in Oracle database.

ORA-01155: the database is being opened, closed, mounted or dismounted

Details of error are as follows.

ORA-01155: the database is being opened, closed, mounted or dismounted

Cause: The requested operation needs the instance to be in a particular state but the state is being changed.

Action: Wait for the open, close, mount, or dismount to complete then retry the operation. 
If necessary, a SHUTDOWN ABORT will always work.

the database is being opened, closed, mounted or dismounted

This ORA-01155 error is related to the requested operation needs the instance to be in a particular state but the state is being changed.

Wait for the open, close, mount, or dismount to complete then retry the operation. If necessary, a SHUTDOWN ABORT will always work.

Then try to switchover again with the following command.

SQL>ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;

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