Error (332000): can't read "pll_ref_clock": no such variable

Description

Due to a problem in the Intel® Quartus® Prime software version 16.1 Update 2 and earlier, you may see the error message above in the fitter stage when your design has an External Memory Interface (EMIF) block tied to lower level of entity. The EMIF PLL reference clock cannot be detected if the design has a wrapper around it.

Resolution

To work around this problem, for the Intel® Quartus® Prime Standard Edition software version 16.1 Update 2, download and install the patch 2.11 from the links below. You must install the Intel Quartus Prime Standard Edition software version 16.1 Update 2 before installing this patch.

Download the version 16.1 Update 2 patch 2.11 for Windows (.exe)

Download the version 16.1 Update 2 patch 2.11  for Linux (.run)

Download the Readme for the Intel Quartus Prime Standard Edition software version 16.1 Update 2 patch 2.11 (.txt)

This problem is fixed in the Intel Quartus Prime Standard and Pro Edition software version 17.0