Recently, Amazon has added an "Error" message to the Prepare Shipments page in Seller Central to warn about box content information sent through Amazon's MWS (Marketplace Web Services). The MWS API is the system third parties, like us, use to communicate with Amazon.
This error message has since been updated so that it now is indicative of if your box content feed has been sent successfully or not. You will know if your feeds are successful in InventoryLab by when you receive a green "Success" message, but now, you will also not be able to move on in Seller Central if they are not.
If you're seeing this message there's a couple of reasons why: Your box contents weren't sent yet, the feed hasn't yet completed, or you received an error for the feed and you have not yet corrected or resent the updated box contents.
If you have received an error, navigate to List > Amazon Listing Errors to determine what the issue is. You'll then correct the box contents and choose to 'Transmit Updated Boxes'.
Below are some errors that you may run into with links to their solutions:
After correcting the issue, be sure to wait for the green success message before heading back over to Seller Central.
Once the feeds are successful, you'll only see this message:
This message is informing you that you chose to use the MWS to provide your box content information, so you cannot choose any of the other box content options in Seller Central.
At this point, you will also notice that the "Total # of boxes" field on this shipment page is automatically filled in, and you will be able to enter in your box weights and dimensions.