Description
You may see this pin placement error in the Intel® Quartus® Prime Software if you have enabled the Passive Serial (PS) configuration scheme and assigned the DCLK pin as a regular I/O pin. You can only assign the DCLK pin as a regular I/O pin if you selected the Active Serial (AS) configuration scheme. When the Passive Serial configuration scheme is selected, the DCLK pin can only be used as a programming pin.
Resolution
Change to the Active Serial configuration scheme or remove the user signal location assignment to the DCLK pin.
Refer to the Device Pin Connection Guidelines for further details.