How to fix Amazon SP API putTransportDetails: access denied?

Question

The putTransportDetails operation in the Fulfillment Inbound Shipment process of the Amazon SP API is giving us problems. Something is denying access. That means we cannot send up transport contents for our shipments, and we cannot automate the transport cost estimation request.

We have many other operations that work just fine. We talked to Amazon Developer Support and they said our set-up and account should be good. We refreshed the application's access tokens to make sure we get access to all features. That did not help.

Our communication signature gets accepted, and we use STS to request temporary credentials to execute the request. We include the session token from STS as the security token for the request. That same handling works in a dozen other calls.

We use python to issue an HTTP request to the REST API that Amazon made: POST https://sellingpartnerapi-na.amazon.com/fba/inbound/v0/shipments/{id}/transport in which we substitute {id} for the shipment id of a shipment plan we created prior to this call.

Here is the documentation: https://developer-docs.amazon.com/sp-api/docs/fulfillment-inbound-api-v0-reference#puttransportdetails

We attempted to post several different kinds of contents: small parcel, and LTL.

All attempts result in the same access denied response.

Any suggestions?

Answer 1

Solution found! We used the wrong HTTP method POST instead of the correct PUT. It's documented that way and even in the name of the operation, and I still managed to overlook it. I hope this helps others!