Description
You may see this error, in the Quartus® II software, during the fitter stage if you cascade a GPLL to a MPLL in your Cyclone® IV GX design.
The Quartus II software may incorrectly auto-place your cascaded MPLL in locations PLL_6 or PLL_7. These two PLL locations only support upstream PLL cascading.
To ensure that your MPLL is correctly placed to support downstream cascading use a PLL location assignment to assign the required MPLL location to either PLL_5 or PLL_8.