[SQL_EXCEPTION_OCCURRED] An SQL exception occurred: Protocol violation

[I]All of sudden we have started getting the following error in the webmethods logs,

Could one of you help me, how to resolve it?

[ART.117.4002] Adapter Runtime (Adapter Service): Unable to invoke adapter service AdapterServices.Database.UserDefined:selectUserDefinedCode. [SQL_EXCEPTION_OCCURRED] An SQL exception occurred: Protocol violation

FYI…

few days back IS has been migrated to 8.2.1.0
The jar file “ojdbc6_g.jar” exists under …/lib/jars/
Enterprise adapter version is : 8.98

Thanks,
Jana.