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ORA-00218:

block size string of control file 'string' does not match DB_BLOCK_SIZE (string)
Cause: The block size as stored in the control file header is different from the value of the initialization parameter DB_BLOCK_SIZE. This might be due to an incorrect setting of DB_BLOCK_SIZE, or else might indicate that the control file has either been corrupted or belongs to a different database.
Action: Restore a good copy of the control file. If the control file is known to be clean set the DB_BLOCK_SIZE to match control file headers block size value.
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