Internal error code, kksgaItLvl_Setup
(Link accessible only by registration to Oracle Support):

Bug 21266085 - ORA-600 [kksgaItLvl_Setup: asc] from a query against an interval partitioned table (Doc ID 21266085.8)


The fix for 21266085 is first included in

12.2.0.1 (Base Release)
12.1.0.2.161018 (Oct 2016) Database Patch Set Update (DB PSU)
12.1.0.2.160719 (Jul 2016) Database Proactive Bundle Patch
11.2.0.4.160719 Exadata Database Bundle Patch (Jul 2016)
12.1.0.2.160419 (Apr 2016) Bundle Patch for Windows Platforms