Oracle Error Message
ORA-12516: TNS:listener could not find available handler with matching protocol stack
Reason for the Error
None of the known and available service handlers for the given SERVICE_NAME support the client’s protocol stack: transport, session, and presentation protocols.
Check to make sure that the service handlers (e.g. dispatchers) for the given SERVICE_NAME are registered with the listener, are accepting connections, and that they are properly configured to support the desired protocols.