UPS error: ‘The Shippers shipper number cannot be used for the shipment’

This usually comes up when there is an error with your UPS account. The best thing to do in this case is to simply contact UPS directly. You can find their contact info here.

The most common issue that can come up is when enetring the wrong password too many times and this way, you get locked out of your account. Please note that UPS can lock you out of your account for up to 24 hours if you try to sign in with the wrong credentials too many times.