Skip constraint checking in NoteSerializer

src/backend/InvenTree/common/serializers.py

@@ -878,6 +878,14 @@ class NoteSerializer(FilterableSerializerMixin, InvenTreeModelSerializer):
 
         read_only_fields = ['updated', 'updated_by']
 
+    def get_unique_together_validators(self):
+        """Skip the auto-generated 'unique_primary_note_per_model' validator.
+
+        That constraint is deliberately enforced by Note.save() by demoting
+        sibling notes, rather than rejecting requests that set 'primary'.
+        """
+        return []
+
     def validate(self, data):
         """Validate note data — templates need no model_id; regular notes require both."""
         data = super().validate(data)