All Oracle Error CodesOracle DBA Forum

NNL-00008:

request not understood by server
Cause: The control program issued a request to an Oracle Names server and the server did not understand the request.
Action: If the server and the control program have different versions, they may be unable to communicate. Check your documentation for version compatibility constraints. If the server and control program are compatible, turn on tracing for further details, and re-execute the failing operation. If the error persists, contact Worldwide Customer Support.