Oracle Message ORA-01618 - redo thread string is not enabled - cannot mount

ERRORredo thread string is not enabled - cannot mount
CAUSEThe INIT.ORA parameter thread requests a thread that is not enabled. A thread must be enabled before it can be mounted.
ACTIONShutdown the instance, change the INIT.ORA parameter and startup mounting a different thread. If the database is open in another instance then the thread may be enabled.