I receive a Critical Warning for the following line in my UCF post-Implementation:
However when I view the Implemented Design the net is on site R7, but not fixed.
If the constraint is locked to a NET, then you should check the hierarchy to ensure that there are no other objects between the net and the I/O port.
PlanAhead does not propagate the constraint through the nets as ISE/NGDBuild did, so the Critical Warning occurs.
In the example above, the correct pin (R7) is used even though PlanAhead removes the constraint because the site being used is for a dedicated feature that requires this pin to be used.
In most cases, when the Critical Warning is issued for a constraint, the site indicated in the constraint will not be used because the UCF file sent to NGDBUILD (written to the runs directory) will not include the constraint.
Below are two available solutions: