Description
Due to a problem in the Quartus® Prime Standard Edition Software version 22.1 and earlier, you might see this internal error when the CLKOUT port on a PLL_REFCLK_SELECT does not drive a FRACTIONAL_PLL. This can occur if the design has a PLL clock output that does not drive any logic.
Resolution
To workaround this problem, either ensure the PLL clock output does drive logic within the device or remove the unused PLL clock output.