Due to a problem with the Intel® Quartus® Prime software version 17.0 and earlier, when generating the Low Latency 40-GbE IP core with the option "Enable KR4" selected, the following error will occur:
Error: alt_eth_ultra_40_0.e40_rx_pll_kr4: "Actual VCO Frequency" (gui_vco_frequency) "625.0" is out of range: "0.0", "600.0".
This error can be safely ignoed. The IP core is still generated and operates correctly.
This problem has been fixed in the Intel® Quartus® Prime software version 17.0 update 1.