Oracle Error Codes

one or more databases could not be contacted for a delete operation

The Data Guard broker could not reach one or more standby databases for either a delete database operation or a delete broker configuration operation.

How to Solve :

This typically indicates a network problem where the standby database is unable to respond to the primary database. In the event of this situation, examine the primary databases Data Guard broker log for to determine which standby databases could not be reached. Then for each standby database not reached, connect to that database and shut down the broker by setting the initialization parameter, dg_broker_start, to false. After the broker has been shut down for the standby database, locate the Data Guard broker configuration files from the standby databases dg_broker_config_file[1|2] parameter values and delete them.