title: Amazon Seller Central - SP-API - GET Labels for shipment
body: <p>I have no previous experience with Amazon MWS so maybe I'm not understanding the whole process flow. Now I'm trying to get labels for shipments I manually created over the Seller Central UI.
  Shipments I created are successfully fetched (Operation: getShipments) and now I have issue when getting the labels.</p>
  <p>Here is my error response from API:</p>
  <pre><code>{'errors': [{'code': 'InvalidInput',
     'message': 'Provided SellerCartonIds are not valid: [[FBAxxxxxxxxxU000001]] for Shipment: [FBAxxxxxxxxx]',
     'details': ''}]}
  </code></pre>
  <p>If I print labels from UI <code>FBAxxxxxxxxxU000001</code> label is printed in pdf - also found out about naming <a href="https://stackoverflow.com/questions/56249677/getuniquepackagelabels-doesnt-use-cartonid-from-post-fba-inbound-carton-conten">here</a>.</p>
  <p>In general, I don't know where to find parameter of package labels <code>PackageLabelsToPrint</code> from <a href="https://github.com/amzn/selling-partner-api-docs/blob/main/references/fulfillment-inbound-api/fulfillmentInboundV0.md#getlabels" rel="nofollow noreferrer">GetLabelsDocs</a>, also I'm not sure if this parameter is same as <code>cartonIdList</code> parameter?</p>
  <p>Here is response if you don't provide <code>PackageLabelsToPrint</code> query param in request:</p>
  <pre><code>{'errors': [{'code': 'InvalidInput',
     'message': &quot;1 validation error detected: Value null at 'cartonIdList' failed to satisfy constraint: Member must not be null&quot;,
     'details': ''}]}
  </code></pre>
  <p>I spent a bit of time on this already and it gets a bit annoying.</p>
  <p>Thanks!</p>