FyroxEngine/Fyrox · warning

Failed to remap handle

Error message

Failed to remap handle {}:{} of node {}!

What it means

Same family as the previous error, but for the reflection-based path: remap_handles_any finds a handle via Reflect (e.g. inside a Vec<Handle<Node>> or Option<Handle<Node>>) and try_map_reflect fails. Because reflection cannot print the typed handle, it logs index:generation instead. The affected handle stays unmapped.

Solutions

1. Rebuild the mapping from a fresh instantiation of the current resource version.
2. Find which reflected field holds the dangling handle (node name is in the message) and clear or reassign it in the prefab.
3. Ensure all referenced nodes exist in the source resource before remapping.
4. If handles intentionally point outside the remapped set, exclude them or extend try_map's delegate to return a valid fallback.

Example fix

// before
#[derive Reflect)] struct Emitter { targets: Vec<Handle<Node>> } // stale handles after re-save
// after
// re-instantiate resource then remap, or clear dangling targets
emitter.targets.retain(|h| graph.is_valid_handle(*h));

// scan reflected fields for handles missing from the map before remapping
fn dangling_reflected_handles<N: Reflect>(root: &dyn Reflect, map: &OldNewMapping) -> Vec<usize> {
    let mut out = vec![];
    root.enumerate::<Handle<Node>>(&mut |h| {
        if h.is_some() && map.try_map(*h).is_none() { out.push(h.index()); }
    });
    out
}

fn valid_reflect_handle(h: &dyn ReflectHandle) -> bool { h.reflect_is_some() && map_contains(h.reflect_index(), h.reflect_generation()) }

let dangling = dangling_reflected_handles(node.as_reflect(), &map);
if !dangling.is_empty() { log::warn!("remap will warn for handles {:?}", dangling); }

When it happens

Trigger: remap_handles / remap_handles_any encountering handles stored inside reflected containers (Vec, Option, HashMap fields) whose value is missing from the old->new mapping.

Common situations: Prefab nodes with arrays of handles (particle systems, sound sources, UI widget lists); remapping after resource re-save changed indices; cloned subgraphs referencing nodes outside the cloned set.

Related errors

• Failed to remap handle
• There are multiple original nodes for
• Graph pool must be empty on load!
• The handle must be valid
• Failed to resolve parent path

AI-assisted analysis of FyroxEngine/Fyrox@76c91aad8e (2026-09-10). Data as JSON: /api/errors/e72973816b5b089c. Report an issue: GitHub.

Appendix: source

Thrown at fyrox-graph/src/lib.rs:243

                ));
            }
            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()
                && !self.try_map_reflect(handle)
            {
                Log::warn(format!(
                    "Failed to remap handle {}:{} of node {}!",
                    handle.reflect_index(),
                    handle.reflect_generation(),
                    node_name
                ));
            }
            mapped = true;
        }

        if mapped {
            return;
        }

        if let Some(inheritable) = entity.as_inheritable_variable_mut() {
            // In case of inheritable variable we must take inner value and do not mark variables as modified.
            self.remap_handles_any(inheritable.inner_value_mut(), node_name, ignored_types);

            mapped = true;

View on GitHub (pinned to 76c91aad8e)