ORA-01567: dropping log string would leave less than 2 log files for instance...

admin

ORA-01567: dropping log string would leave less than 2 log files for instance string
(thread string)
Cause: Dropping all the logs specified would leave fewer than the required two
log files per enabled thread.
Action: Either drop fewer logs or disable the thread before deleting the logs. It
may be possible to clear the log rather than drop it.