I have recently began re-work a custom .NET applications and have migrated it from .NET3.5 on SP2010 (dev on VS2010) to .NET4.52 on SP2016 (dev on VS2017). Everything has ported fairly seamlessly. However, I have been diagnosing an issue with the BCS data retrieval using the FindFiltered method into IEntityInstanceEnumerator (IEIE) interface. When the call completes, and the subsequent MoveNext call is executed, an error occurs indicating: External ItemEnumerator is closed The model I have imported and setup still contains all valid pieces and permissions...each item container ReadList and ReadItem operations. I'm now using Kerberos/Claims w/ valid SPNs setup. I can see the valid query call to SQL both in ULS logs and in SQL profiler. I have turned on VERBOSEX and retrieved no additional clues. The odd thing is in other parts of the application, if we push the returned IEIE into the CreateDataTable, we can process this...so it seems the data exists. I'm trying not to have to refactor several areas if I can find a reason why this would be occurring. Thanks for any ideas (and I will provide more info as requested).