we have implemented ESS/MSS in our landscape and are facing an issue in trying to maintain some JCo destinations.
the problem is that when we try to maintain any JCo metadata destination (e.g. SAP_R3_HumanResources_Metadata, SAP_R3_SelfServiceGenerics_Metadata, etc) using the definition field "useDefinedUser = JCO_METADATA", the details get saved but upon testing or pinging the destination, we get the below error.
com.sap.mw.jco.JCO$Exception: (103) RFC_ERROR_LOGON_FAILURE: SNC name and specified user/client do not match
to be sure of user id/password, we checked the logon for the above mentioned user id JCO_METADATA in the relevant client by changing the user type from communication to dialog and were able to log on without any problems after which we switched back to communication. we have also referred to the "Troubleshooting SAP Java Connector" guide but it only lists RFC communications error for user id/password. further, we have also not been able to find the above error on Notes.