The framework throws javax.validation.ValidationException or its subclass exceptions, such as javax.validation.ConstraintViolationException, when the Bean Validation rules that you set on the model class fails at runtime. The JAX-RS runtime will report the validation error back to the client with a 500 (internal server error) HTTP status code. You can override the default validation exception handling by providing a custom javax.ws.rs.ext.ExceptionMapper class. We discussed ExceptionMapper a while ago in the Mapping exceptions to the response message using ExceptionMapper section.