ORA-01620

Error: ORA-01620: no public threads are available for mounting

Causa: The value of the initialization parameter THREAD is zero, its default value. There are no threads which have been publicly enabled, and not mounted.

Acción: Shut down the instance, change the value of the initialization parameter to a thread which is privately enabled and not mounted. If the database is open in another instance, then a thread may be publicly enabled.