oracle error - ORA-00280: change string for thread string is in sequence #string

ORA-00280:	change string for thread string is in sequence #string
Cause:	This message helps to locate the redo log file with the specified change number requested by other messages.
Action:	Use the information provided in this message to specify the required archived redo log files for other errors.

oracle error - ORA-00279: change string generated at string needed for thread string

ORA-00279:	change string generated at string needed for thread string
Cause:	The requested log is required to proceed with recovery.
Action:	Please supply the requested log with "ALTER DATABASE RECOVER LOGFILE <file_name>" or cancel recovery with "ALTER DATABASE RECOVER CANCEL".

ORA-00278:	log file 'string' no longer needed for this recovery
Cause:	The specified redo log file is no longer needed for the current recovery.
Action:	No action required. The archived redo log file may be removed from its current location to conserve disk space, if needed. However, the redo log file may still be required for another recovery session in the future.