ORA-16802: downgrading redo transport mode from SYNC disallowed

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ORA-16802:downgrading redo transport mode from SYNC disallowed
Cause: An attempt was made to downgrade the redo transportmode of a standby
database from SYNC to ASYNC when the configuration was in Maximum
Protection or Maximum Availability mode and the primary database was a RAC
database. This was not disallowed even though there may have been other
standby databases with redo transport modes set to SYNC to support the
protection mode.
Action: Doone of the following if the redo transport mode of the standby must be
downgraded:
- Shut down all instances of the primary database and restart one instance withthe
initialization parameter CLUSTER_DATABASE set to FALSE. Downgrade the redo
transport mode of the standby database of interest. Then, shutdown theinstance,
set the the CLUSTER_DATABASE initialization parameter to TRUE, and restart all
primary database instances.
- Downgrade the protection mode to Maximum Performance mode and then,
downgrade the redo transport mode of the standby database of interest. Finally,
upgrade the protection mode. This will require a restart of all primary database
instances if upgrading to Maximum Protection mode. Note that the above only
works when there is at least one standby database in the configuration that hasits
redo transport mode set to SYNC.