When shipping with Amazon Seller Fulfilled Prime, the below error will be shown on your shipment history if you reach the API limit set by Amazon.

(503) Amazon API request limit reached. Please wait a few seconds and retry this shipment

Waiting a few seconds before retrying your shipments will resolve the issue. If you repeatedly see this message, shipping in smaller batches from your sales channel would help. We are working to improve how requests are queued with Amazon SFP to remove as much friction from the shipping process as possible.

If you have questions, please reach out to support.