I created a custom validator by subclassingUniqueTogetherValidator and overriding its__call__ method. This allows me to catch the default error and raise my ownValidationError with a custom message and error code.

classCustomUniqueTogetherValidator(UniqueTogetherValidator):def__call__(self,attrs,serializer):self.enforce_required_fields(attrs,serializer)try:super().__call__(attrs,serializer)exceptserializers.ValidationErrorasexc:            [msg]=exc.detailraiseserializers.ValidationError(str(msg),code="custom_unique_constraint"            )fromexcclassMySerializer(serializers.ModelSerializer):classMeta:model=MyModelfields="__all__"validators= [CustomUniqueTogetherValidator(queryset=MyModel.objects.filter(...).all(),fields=["field1","field2"],message="My custom message."            ),        ]

⚠️ When you override the validators attribute in your serializer’s Meta, it replaces all automatically generated validators based on model constraints (https://github.com/encode/django-rest-framework/blob/master/rest_framework/serializers.py#L1561-L1563). DRF will no longer auto-generate them — so you must explicitly define any additional validators you need (e.g., for other UniqueConstraints or CheckConstraints).

If an issue is opened based on this discussion, I’d be happy to submit a PR with a fix.