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

Oracle Error Message

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

Reason for the Error

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

Solution

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