Prerequisites for Validating Message Schemas
Before you can enable schema validation, you must build or import a message schema for the message and message version.
If no message schema is present for service operations that contain regular nonrowset-based messages or container messages, it is not possible to enable validation.
For service operations that contain rowset-based messages, the system will attempt to generate a schema if one is missing. If the system is able to successfully generate a message schema for a rowset-based message, validation is enabled.