Selling Partner API return MissingAuthenticationToken


#1

Hi All,

We are getting a “MissingAuthendicationToken” error message when we call the Selling Partner API to access our Vendor Central Direct Fulfillment order. The error message is

string(135) “{
“errors”: [
{
“message”: “Access to requested resource is denied.”,
“code”: “MissingAuthenticationToken”
}
]
}”

We have followed the SellingPartnerApiDeveloperGuideForVendor.md document. We made a LWA HTTPS call to get an access token and use it to construct a HTTP header with the Amazon Signature Version 4 signing. The following is a sample of the header and endpoint.

[“headers”]=>
array(4) {
[“X-Amz-Access-Token”]=>
string(332) “Atza|IwE…”
[“user-agent”]=>
string(58) “Company/0.1 (Language=PHP; Host=myhost)”
[“X-AMZ-Date”]=>
string(16) “20201221T170147Z”
[“Authorization”]=>
string(227) “AWS4-HMAC-SHA256 Credential=AK…/20201221/us-east-1/execute-api/aws4_request,SignedHeaders=host;user-agent;x-amz-access-token;x-amz-date,Signature=9a931…”
}
[“endpoint”]=>
string(99) “https://sellingpartnerapi-na.amazon.com/vendor/directFulfillment/orders/v1/purchaseOrders/XXXXXXXXX
[“action”]=>
string(11) “execute-api”

We seem to follow all the requirements but we are getting the error. We have opened a case with Amazon Support for a week and haven’t gotten any reply. Can anyone provide some suggestions?

Thank you!
Peter