When processing orders you might come across the "2488 ERROR Invalid ShipmentSpecialServiceType" error.
This error is shown when you are trying to process an order using FedEx One Rate, but it's not enabled for your FedEx account yet. You can either:
A) Contact your FedEx representative or manager to request activation of FedEx One Rate for your account
B) Disable FedEx One Rate temporarily from your Billing Account in techShip in order to process the order some other way