Constraint matches nothing

An Add Constraint rule's filter finds nothing in the scenario to apply to, such as no lane from an Export site carrying Food. Network Optimization stops rather than solve without the rule.

What to do

Check the values the filter compares in the Add Constraint node's settings panel, or in its Constraint Table row, for typos: tags, types, names, transport modes. Then make sure the scenario has what the rule is written for, or remove the rule.

Where it comes from

Shown by Network Optimization. It is one of the messages about a node.