ORA-64772
downstream replication server: string is not accessible
Cause
The specified downstream replication server was not running, was not accesible, had incorrect credentials for the replication user in the upstream wallet, or was in the process of starting up or shutting down.
Action
If the credentials are incorrect, correct the credentials. Otherwise, the incident is marked as FIXED once the downstream replication server comes back online or is accessible over the network.