Greetings! If you're getting this error, that means that there is something in your code somewhere that ends up making more than one request within our throttling window. Double-check your code - for example in your holding all transfers situation, once you're done holding it do you continue to send requests as fast as possible? Our throttling requires you to provide a gap of time between each individual request, and if you get this message it means that - either intentionally or not - you're attempting to perform two requests of the same type within our throttling window. If - theoretically - the operation you're performing is an item transfer, you would have to wait a whole second between getting the response for the last request and initiating the call for the new request.