Cause: An attempt to open the thread failed because it is necessary to switch redo generation to another online log, but all the other logs are being cleared or need to be archived before they can be used.
Action: If the ALTER DATABASE CLEAR LOGFILE command is still active, then wait for it to complete. Otherwise, reissue the CLEAR command. If there are other online logs for the thread that are not being cleared, then archive the logs.
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