Why does checkout say “No shipping rates available”?

“No shipping rates available” usually means the buyer’s address doesn’t match any shipping zone, the product’s weight or shipping profile excludes it, or a carrier-calculated rate (Carrier Service API) is timing out or returning an error. Overlapping or duplicated zones can also silently knock out rates. We audit your shipping profiles, zones and any carrier/app integration, then reproduce a real cart to confirm the fix.