The error means that the service is not available. Please check your address in the settings and the client’s address to be sure that UPS is trying to use a valid ZIP code and country. If you still get this error, that service may actually be unavailable in the UPS for your or client’s address.

If you are using credentials for testing or development purposes, it may not return all services, so the error wouldn’t be shown to real clients.

Actually, I see that there is an error 500 on your website, so I cannot see the shipping methods that you’ve set.

Best regards,

Kind regards,
?ukasz