ORA-16549: invalid string
Cause: An invalid or NULL string value was specified.
Action: Correct command parameters and retry.
ORA-16550: truncated result
Cause: A string property value was truncated due to insufficient buffer size.
Action: Specify a larger receive buffer.
ORA-16551: short string copied
Cause: A string property value that did not fill the receive buffer was placed in the receive buffer.
Action: This is an informational message only.
ORA-16552: an error occurred when generating the CLIENT OPERATION table
Cause: An error occurred while Data Guard broker was generating the CLIENT OPERATION table.
Action: See the next error message for more detailed information. Execute the action described in the next error or contact Oracle Support Services.
ORA-16555: database is not active
Cause: An operation was attempted on a database that was not active. not active.
Action: Verify that the database is active and retry the operation.
ORA-16556: observer version mismatch
Cause: This version of the observer was incompatible with the version of the specified Oracle database server to which the observer had been connected. This observer client cannot be used to observe the specified Oracle server.
Action: Use a version of the observer that is compatible with the Oracle database server to be observed.
ORA-16557: database is already in use
Cause: An attempt was made to create a duplicate database in the broker configuration.
Action: Check the database to be added to ensure there are no duplicates.
ORA-16558: database specified for switchover is not a standby database
Cause: An attempt was made to switchover to a database that was not a standby database.
Action: Locate an enabled standby database and select that database as the target of the switchover.
ORA-16561: cannot remove an active instance
Cause: The instance to be removed was running.
Action: Shut down the instance and reissue the REMOVE command.
ORA-16568: cannot set property string
Cause: The specified property could not be modified because it was either a monitorable property or a property that did not exist.
Action: Retry the command with a valid configurable property.
ORA-16569: Data Guard configuration is not enabled
Cause: The requested operation required that broker management of the Data Guard configuration must be enabled.
Action: Enable the Data Guard configuration and reissue the request.
Above are list of Oracle Database Errors or Warnings from Error ORA-16549 to ORA-16569 received while performing certain operation against Oracle Database or related products.
What are Oracle Database Error Messages?
Oracle Error Messages may be returned while using products which are part of Oracle Database. Each Oracle Database Error or Warning Message mentioned above contains the Warning or Error Message Statement, a short explanation of the probable causes of the Error message, and a recommended action.
Hope this was helpful.
Information about Oracle Database Error Messages or Warning Messages on Windows and Linux Operating Systems.