Description
You may get such a pin placement error in the Quartus® II software if you have also enabled the Partial Reconfiguarion (PR) pins in your project. When the PR pins are enabled, the dual purpose configuration data pins used for 16-bit Fast Passive Parallel (FPPx16) mode can only be used for configuration purposes.
Resolution
Disable the PR pins in your project or remove the user signal location assignment to the affected dual-purpose pin.