A client has been seeing this error when holding sessions open over HS for lengthy periods of time (greater than an hour or so).
Some workarounds that have worked are:
- when possible, issue, alter session close database link, and re-open it for subsequent queries
- Set INBOUND_CONNECT_TIMEOUT_<listener_name>=0 in listener.ora
- Set SQLNET.INBOUND_CONNECT_TIMEOUT=0 in sqlnet.ora