Error 21916045 — Invalid AdditionalShippingCost

Shipping cost for additional items may not be greater than base shipping cost. Your Additional Shipping Cost has been reset to match the Shipping Cost value.

eBay shipping errors stem from missing/invalid shipping service codes, incorrect package dimensions, weight outside service limits, or destinations not allowed for the shipping service selected.

1. Use valid ShippingServiceCode values from the GeteBayDetails API — these vary by site (US, UK, etc.) and change periodically.
2. Provide accurate package dimensions (L×W×H) and weight — eBay calculates rates and rejects out-of-bounds values.
3. Don't ship to destinations the carrier doesn't serve — use ExcludeShipToLocation to remove unserviceable countries/regions.
4. Set up a shipping policy in Seller Hub → Business Policies — much easier than per-listing shipping settings.

• Missing shipping rate for international ShipToLocations — listing fails internationally even if domestic works
• Using a USPS Flat Rate service code with package dimensions that don't fit a flat rate box