bevyengine/bevy · error

expected bundle `{}` to be named struct or tuple

Error message

expected bundle `{}` to be named struct or tuple

What it means

Panic in ReflectBundleFns::from_reflect (insert path): dynamic reflection produced a bundle value whose ReflectRef shape is neither Struct nor Tuple (e.g. a Map/List or a unit), so its fields cannot be applied field-wise onto the entity. The message names the offending bundle type.

Source

Thrown at crates/bevy_ecs/src/reflect/bundle.rs:173

                let bundle = entity.world_scope(|world| {
                    from_reflect_with_fallback::<B>(reflected_bundle, world, registry)
                });
                entity.insert(bundle);
            },
            apply: |mut entity, reflected_bundle, registry| {
                if let Some(reflect_component) =
                    registry.get_type_data::<ReflectComponent>(TypeId::of::<B>())
                {
                    reflect_component.apply(entity, reflected_bundle);
                } else {
                    match reflected_bundle.reflect_ref() {
                        ReflectRef::Struct(bundle) => bundle
                            .iter_fields()
                            .for_each(|(_, field)| apply_field(&mut entity, field, registry)),
                        ReflectRef::Tuple(bundle) => bundle
                            .iter_fields()
                            .for_each(|field| apply_field(&mut entity, field, registry)),
                        _ => panic!(
                            "expected bundle `{}` to be named struct or tuple",
                            // FIXME: once we have unique reflect, use `TypePath`.
                            DebugName::type_name::<B>(),
                        ),
                    }
                }
            },
            apply_or_insert_mapped: |entity,
                                     reflected_bundle,
                                     registry,
                                     mapper,
                                     relationship_hook_mode| {
                if let Some(reflect_component) =
                    registry.get_type_data::<ReflectComponent>(TypeId::of::<B>())
                {
                    reflect_component.apply_or_insert_mapped(
                        entity,
                        reflected_bundle,

View on GitHub (pinned to 396ca72708)

Solutions

1. Ensure the reflected data deserializes into the bundle's Struct/Tuple shape (e.g. via ReflectDeserializer to the bundle type)
2. Register and construct the bundle type itself rather than a dynamic proxy
3. Handle the dynamic value with from_reflect_with_fallback on the concrete bundle type

When it happens

Trigger: Thrown at crates/bevy_ecs/src/reflect/bundle.rs:173 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of bevyengine/bevy@396ca72708 (2026-08-20). Data as JSON: /api/errors/b2d911d6b6b5c3d5. Report an issue: GitHub.