The following is the ORA-01211 error message, you can learn the cause and solution of the Oralce error.
ORA-01211 Oracle7 data file is not from migration to Oracle8
Cause: The file is not a copy of the file LAST used under Oracle7. This datafile is either a backup taken from before the migration, or the database was opened by Oracle7 after the migration utility was run. When converting a database from Oracle7 to Oracle8, the migration program MUST be the LAST utility to access the database under Oracle7. Only the datafiles that were current when the migration was done may be accessed by Oracle8.
Solution: Have operating system make correct datafile available to database, or repeat the Oracle7 to Oracle8 migration. Make sure that database is NOT opened after migration utility is run.
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