Oracle : Ошибка ORA-16574

"switchover disallowed when required databases are shut down"
*Cause: Switchover failed because either the primary database or the
designated standby database were shut down.
*Action: Ensure that the primary and standby databases are running and
that primary database is shipping redo data to the designated
standby database. Also ensure that that the designated standby
database is applying the redo data received from the primary

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