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ORA-01244:

unnamed datafile(s) added to control file by media recovery
Cause: Media recovery with a backup control file or a control file that was rebuilt, encountered the creation of a datafile that was not in the control file. An entry has been added to the control file for the new datafiles, but with the file name UNNAMEDnnnn, where nnnn is the file number. Attached errors describe the file names that were originally used to create the files.
Action: Rename the files to valid file names and resume recovery. If necessary the command ALTER DATABASE CREATE DATAFILE may be used to create a file suitable for recovery and do the rename. If the file is not going to be recovered then take it offline with the FOR DROP option.