We have run for the last 7 years without issue against the same oracle 11g database using SSRS 2008 with an OracleClient data source. As soon as we upgraded to SSRS 2016 and had to switch to ODP.NET, we are randomly getting ORA-12571 errors. It may be important to note that when the error does show up, users can hit refresh and it runs just fine.
The error in the reporting services log looks like this:
"Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: An error has occurred during report processing. ---> Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: Query execution failed for dataset 'DataSetOrders'. ---> Oracle.ManagedDataAccess.Client.OracleException: Oracle error ORA-12571 encountered ---> OracleInternal.Network.NetworkException: Oracle error ORA-12571 encountered ---> System.Net.Sockets.SocketException: An established connection was aborted by the software in your host machine"
The error in the browser looks like this:
