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ORA-00296:

maximum number of files (string) exceeded for RECOVER DATAFILE LIST
Cause: The RECOVER DATAFILE LIST command specified more datafiles than are allowed by the DB_FILES initialization parameter. This error occurs when doing recovery with Recovery Manager, and the instance has been started with a DB_FILES parameter specifying fewer datafiles than recovery manager needs to recover to satisfy the user's RECOVER command.
Action: Re-start the instance with a higher value for DB_FILES.