All Oracle Error CodesOracle DBA Forum

ORA-01154:

database busy. Open, close, mount, and dismount not allowed now
Cause: Some operation is in progress that expects the opened/mounted state of this instance to remain the same.
Action: Wait for the operation to complete then retry. If attempting to do a shutdown, SHUTDOWN ABORT will work. If this is a shutdown of a standby database that is operating in NO DATA LOSS mode, you must shutdown the primary database first.