When processing orders you might come across the "Address Validation failed - 1000 ERROR Authentication Failed" error.
This error is shown when the FedEx Address Validation services are not enabled for the FedEx account.
To solve the issue, reach FedEx Web Services and request enabling this option for your account.
While you resolve the issue with FedEx, you can turn off address validation as a temporary workaround, by selecting "No Validation" at the Billing Account of your Client in techShip as described here: