Error in Constraint Checker: Invalid <constraint_type> constraint -  the <argument> port or pin list is empty

Where <constraint_type> is multicycle, false_path, or max_delay, and <argument> is -from, -to, or -through.

The exact error message varies according to your constraint and argument. For example:
Error in Constraint Checker: Invalid false_path constraint - the -from port or pin list is empty.

No <–from OR -through OR -to> port or pin list has been supplied for the constraint.

Action

Enter at least one port or pin for the <-from OR -through OR -to> argument.