No MWS Authorization exists: Amazon Selling Partner API

Question

Whenever I am migrating any customer from MWS to SP I am getting "No MWS Authorization exists" error. For me the situation is different If I migrate the EU region connection then its works fine. Only facing issues with US region connections.

To get the grantless LWA access token (code) I used the https://sellingpartnerapi-{customer.region}.amazon.com/authorization/v1/authorizationCode which works fine.

To exchange the code for a refresh token I use the seller mwsAuthToken , sellingPartnerId , and my developerId associated with the seller region.

What is the meaning of this error:

[{'code': 'InvalidInput', 'message': 'No MWS Authorization exists', 'details': ''}]

Related questions with no answer:

a.https://github.com/amzn/selling-partner-api-docs/issues/2252

b. Amazon SP-API: Getting No MWS Authorization exists when requesting authorization code via MWS token

Answer 1

The docs on this are spread all over the place and admittedly a bit hard to find. You mentioned changing {customer.region} in the url, and if it's working for EU, then you're probably getting the migration token properly, so it sounds like the only thing remaining different from EU to US is the region being used in the authorization signature.

EU region sellers use eu-west-1/execute-api . US sellers use us-east-1/execute-api .

Also, so you have it:

• A walk-through on this process in docs: https://developer-docs.amazon.com/sp-api-blog/docs/migrate-seller-authorizations-from-mws-to-sp-api#step-1-generate-a-grantless-lwa-access-token .
• A postman collection you can import: https://github.com/amzn/selling-partner-api-models/tree/main/models/authorization-api-model .
• And the endpoint reference: https://developer-docs.amazon.com/sp-api/docs/sp-api-endpoints