Cause: The redo block indicated by the accompanying error, is not valid. It has a checksum that does not match the block contents.

Action: Perform 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 UNARCHIVED option. This must be followed by a backup of every datafile to insure recoverability of the database. Restore the correct file or reset logs.