FyroxEngine/Fyrox · warning

Failed to remap handle

Error message

Failed to remap handle {} of node {}!

What it means

remap_handles_any walks every entity of a graph node and rewrites Handle<N> values through try_map (old->new id mapping after resource instantiation). When a handle is Some but not present in the mapping, this warning is logged; the handle is left unmapped and will likely point at the wrong node or be dangling.

Solutions

1. Re-instantiate the resource so the mapping covers all current handles (use ResourceData::instantiate or ensure instantiate_graph built the map).
2. Log/inspect the missing key: the unmapped handle index tells you which node in the source prefab is absent from your map.
3. Regenerate the old->new mapping from the actual resource version instead of a stale cached map.
4. Remove or fix nodes in the prefab that reference deleted nodes (the warning at fyrox-graph/src/lib.rs:1472 often precedes this).

Example fix

// before
let map = old_stale_mapping.clone();
graph.remap_handles(&map);
// after
let mut map = old_stale_mapping.clone();
for (old, new) in resource.mapping() { map.entry(*old).or_insert(*new); }
graph.remap_handles(&map);

// verify all handles are mappable before remap
fn all_mappable<N, M>(graph: &Graph, map: &M) -> bool
where M: HandleMapDelegate<N> {
    graph.linear_iter().all(|n| {
        // reflect over node fields containing Handle<N> and check map presence
        check_node_handles(n, map)
    })
}

fn is_valid_source<N>(h: Handle<N>, src: &Graph) -> bool { src.is_valid_handle(h) }

// remap is warning-based; detect unmapped handles afterwards
graph.remap_handles(&map);
assert!(graph.linear_iter().all(|n| node_handles_mapped(n, &map)));

When it happens

Trigger: Calling Graph::remap_handles / remap_handles_any with a mapping whose keys do not cover all non-null handles stored in node properties (e.g. mapping built from a different resource instance, or handles pointing to nodes deleted from the source resource).

Common situations: Instantiating a scene prefab whose nodes were edited/re-saved (indices changed) after an instance was cached; cloning nodes across graphs without regenerating the handle map; manual edits to resource files. The typed Handle<N> path fires when the field is stored directly as Handle<N>.

Related errors

• Failed to remap handle
• There are multiple original nodes for
• Graph pool must be empty on load!
• The handle must be valid
• Instantiating a model from a resource that is not loaded

AI-assisted analysis of FyroxEngine/Fyrox@76c91aad8e (2026-09-10). Data as JSON: /api/errors/aebada5d5baa779a. Report an issue: GitHub.

Appendix: source

Thrown at fyrox-graph/src/lib.rs:222

        let name = node.name().to_string();
        self.remap_handles_any(node, &name, ignored_types);
    }

    pub fn remap_handles_any(
        &self,
        entity: &mut dyn Reflect,
        node_name: &str,
        ignored_types: &[TypeId],
    ) {
        if ignored_types.contains(&(*entity).type_id()) {
            return;
        }

        let mut mapped = false;

        if let Some(handle) = entity.downcast_mut::<Handle<N>>() {
            if handle.is_some() && !self.try_map(handle) {
                Log::warn(format!(
                    "Failed to remap handle {} of node {}!",
                    *handle, node_name
                ));
            }
            mapped = true;
        }

        if mapped {
            return;
        }

        // Handle derived entities handles.
        if let Some(handle) = entity.as_handle_mut() {
            if handle
                .type_info_ref()
                .derived_types
                .contains(&TypeId::of::<N>())
                && handle.reflect_is_some()

View on GitHub (pinned to 76c91aad8e)