The FRAME_ECCE3 primitive is reserved. This primitive is used when implementing the Soft Error Mitigation (SEM) IP.
The FRAME_ECCE3 in Kintex UltraScale and Virtex UltraScale FPGAs is significantly different than the FRAME_ECCE2 of 7 series devices. The FRAME_ECCE2 does not migrate directly to the FRAME_ECCE3, but the SEM IP automatically adapts to the new architecture. Note that the SEM IP is not supported in the KU025 device.