Google Merchant Center requires shipping cost for each of the items in the feed so that Google Ads can show it in ads. If a shipping cost cannot be derived for the item, it is rejected with "Missing value [shipping]" error.
Shipping in GMC must align with the shipping settings in the shop so that the derived cost in GMC is equal or higher than the shipping charge on checkout, or Google may suspend the account.
Shipping cost can be provided to Google Merchant Center in several ways:
Shipping services entries can be added to GMC "Shipping and returns" settings, which must be in the feed currency and target the feed countries. These entries can be added manually in GMC, but the recommended way is to enable the app to do "Shipping synchronization" for the merchant account in question.
By shipping synchronization, the app will import the current shipping settings in the store to GMC, converting currency if required. Shopify custom shipping rates/custom shipping profiles and rates from Advanced Shipping Rules app are supported.
For shipping synchronization, the merchant account must firstly be connected to the app via the "Connect account" button in the Feeds tab:
Shipping cost can be included in the feed data of the items. This can be done at feed level, collection level or product level feed settings.
