Error authenticating to SAP host: com.sap.mw.jco.JCO$Exception: (103) RFC_ERROR_LOGON_FAILURE: User XXXXXXXX has no RFC authorization for function group SYST.
Looks to me like the user doesn't have rights to make RFC calls -- would that be correct?
The user you are using to create the JCo connection instance does not have authority to access that specific RFC. Depending on what the function is, you will need to update the connecting user's profile in SAP. If you have access to a sandbox, try testing with a user that has the 'SAP_ALL' profile.
This was first published in July 2003