Cause: A change number found in the redo log is lower than a previously encountered change number. The log is corrupted in some way. The corruption may be at the earlier change or at this one. Action: Do recovery with a good version of the log or do time based recovery up to the indicated…

Cause: Some type of redo log corruption has been discovered. This error describes the location of the corruption. Accompanying errors describe the type of corruption. Action: Do recovery with a good version of the log or do incomplete recovery up to the indicated change or time.

Cause: An IO error has occurred while writing the log Action: Correct the cause of the error, and then restart the system. If the log is lost, apply media/incomplete recovery.

Cause: Check of log file header at database open found that an online log has log reset data that is different from the control file. The log is probably an incorrectly restored backup. Action: Restore correct file or reset logs.

Cause: An I/O failure occurred when attempting to re-create an online as part of either ALTER DATABASE OPEN RESETLOGS or ALTER DATABASE CLEAR LOGFILE command. Action: Correct the file/device as indicated by accompanying errors.

Cause: An IO error occurred while reading the log described in the accompanying error. Action: Restore accessibility to file, or get another copy of the file.

Cause: A change record in the redo log contains lengths that do not add up to a consistent value. The log is corrupted in some way. Action: Do recovery with a good version of the log or do time based recovery up to the indicated time.

Cause: Attempting to enable a thread with all logs needing to be archived, and media recovery has been enabled. There is no log that can be made the new current log for the thread. Action: Archive a log for the thread or disable media recovery.

Cause: The operating system was unable to determine the blocksize for the given filename. Action: Consult the accompanying error message, and correct the device or specify another filename.

Cause: The block header on the redo block indicated by the accompanying error, is not reasonable. Action: Do recovery with a good version of the log or do time based recovery up to the indicated time. If this happens when archiving, archiving of the problem log can be skipped by clearing the log with the…