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400 - Allocation Failed
The error code
allocation_failed will be returned when an attempt has been made to allocate a shipment, but there were no valid carrier services available.For example, if you ask SortedPRO to allocate a shipment using a specific service group, but not of the carrier services within that service group can meet the requirements of the shipment, you will receive an error code of allocation_failed.
Allocation failures will return an HTTP status code of
521. Whilst this is not an official or standard HTTP status code, it is returned to enable automated integrations to distinguish between failures in the Shipments API (e.g. HTTP status code 500), errors relating to the properties of the request (e.g. HTTP status code 400), and errors specifically relating to a failure to allocate a shipment.