FPGA 一问题解决

ERROR:ConstraintSystem:59 - Constraint <NET "OscOut_n" S>: NET "OscOut_n" not found. Please verify that: 1. The specified design element actually exists in the original design. 2. The specified object is spelled correctly in the constraint source file.
What is the cause of this issue, and how can I resolve it?

 

Solution

 

There is a known issue where constraint information is being kept in an internal constraints database even after being removed from the source files. A CR is under investigation to correct this problem in a future ISE revision. Meanwhile, the problem can be corrected by performing the operation, "Cleanup Project Files" from the Project pulldown menu.