We are currently planning an server migration. We have our current server on SDE 10.1 on Oracle 11 Currently our editors are on ArcGIS 10.1 with Oracle client 11.2
Our new server is setup and ready for testing. It is at SDE 10.3.1 on Oracle 12c. However when ArcGIS Desktop existing clients try to connect to it they are getting an error:
Failed to connect to database. Underlying DBMS error [unknown Error No extended error]
.
I had thought that newer versions of SDE were backwards compatible with older ArcGIS desktop clients. Is there a connection setting that has to change? The connection settings we are using work fine with ArcGIS desktop 10.3.1 :