ORA-00204

Error: ORA-00204: error in reading (block string, # blocks string) of controlfile

Causa: A disk I/O failure was detected on reading the control file.

Acción: Check that the disk is online. If it is not, bring it online and shut down and restart Oracle. If it is online, then look for operating system reasons for Oracle's inability to read the disk or control file. See the Oracle9i Database Administrator's Guide for information on recovering from the loss of a control file. See also your operating system-specific Oracle documentation.