Oracle : Ошибка ORA-15166

"cluster in rolling downgrade from version [%s] to [%s]"
*Cause: The current software version of the instance was incompatible with
the rolling downgrade operation of the cluster.
*Action: The version number of new member instance must be one of the two
versions involved in the rolling downgrade.

Попробовать перевести

Поискать эту ошибку на форуме