Error responses for our APIs will vary depending on the specific API that you are using, refer to the documentation for further detail on an individual service.
There are common authentication errors for APIs that use WS-Security, see the Authentication errors article for detail.
SOAP APIs that use WS-Security will also validate the request before processing. If the request is not valid to the API's schema then you will receive a status 500 response with SOAP fault:
<faultstring>An internal error occurred</faultstring>