Oracle Error Message
ORA-01624: log string needed for crash recovery of instance string (thread string)
Reason for the Error
A log cannot be dropped or cleared until the thread’s checkpoint has advanced out of the log.
Solution
If the database is not open, then open it. Crash recovery will advance the checkpoint. If the database is open force a global checkpoint. If the log is corrupted so that the database cannot be opened, it may be necessary to do incomplete recovery until cancel at this log.