BabylonJS/Babylon.js · error · Error

${context}/type: Invalid value ${accessor.type}

Error message

${context}/type: Invalid value ${accessor.type}

What it means

Index accessors must be of type SCALAR per the glTF 2.0 spec. When _loadIndicesAccessorAsync receives an accessor whose type is VEC2, VEC3, VEC4, or MAT*, it throws this error before any data is loaded. Indices are inherently a flat list of scalars.

Source

Thrown at packages/dev/loaders/src/glTF/2.0/glTFLoader.pure.ts:2187

            });
        }

        return accessor._data;
    }

    /**
     * @internal
     */
    public _loadFloatAccessorAsync(context: string, accessor: IAccessor): Promise<Float32Array> {
        return this._loadAccessorAsync(context, accessor, Float32Array) as Promise<Float32Array>;
    }

    /**
     * @internal
     */
    public _loadIndicesAccessorAsync(context: string, accessor: IAccessor): Promise<IndicesArray> {
        if (accessor.type !== AccessorType.SCALAR) {
            throw new Error(`${context}/type: Invalid value ${accessor.type}`);
        }

        if (
            accessor.componentType !== AccessorComponentType.UNSIGNED_BYTE &&
            accessor.componentType !== AccessorComponentType.UNSIGNED_SHORT &&
            accessor.componentType !== AccessorComponentType.UNSIGNED_INT
        ) {
            throw new Error(`${context}/componentType: Invalid value ${accessor.componentType}`);
        }

        if (accessor._data) {
            return accessor._data as Promise<IndicesArray>;
        }

        if (accessor.sparse) {
            const constructor = GLTFLoader._GetTypedArrayConstructor(`${context}/componentType`, accessor.componentType);
            accessor._data = this._loadAccessorAsync(context, accessor, constructor);
        } else {

View on GitHub (pinned to 0592b347b8)

Solutions

1. Change the indices accessor type to "SCALAR" and regenerate its data.
2. Point primitive.indices at the correct SCALAR accessor.
3. Re-export the mesh with a compliant exporter.
4. Run glTF-Validator to find all mis-typed accessors.

Example fix

// before
"accessors": [{ "type": "VEC3", "componentType": 5125, "count": 36 }]
// after (indices)
"accessors": [{ "type": "SCALAR", "componentType": 5125, "count": 36 }]

for (const prim of gltf.meshes?.flatMap(m => m.primitives) ?? []) {
  const acc = gltf.accessors?.[prim.indices!];
  if (acc && acc.type !== "SCALAR") {
    throw new Error(`Indices accessor type must be SCALAR, got ${acc.type}`);
  }
}

function isScalarAccessor(acc: { type: string }): acc is { type: "SCALAR" } {
  return acc.type === "SCALAR";
}

try { await loadAsset(); } catch (e) {
  if (/\/type: Invalid value/.test((e as Error).message)) {
    // reject or repair the asset before retrying
  }
}

When it happens

Trigger: A primitive's indices accessor referencing an accessor with type != "SCALAR"; usually a malformed asset or an exporter writing the wrong type field.

Common situations: Buggy exporters pointing indices at a vector accessor, hand-edited glTF JSON, converters that reused an attribute accessor as indices.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• ${context}/componentType: Invalid value ${accessor.component
• ${context}: Camera orthographic properties are missing
• ${context}: Invalid camera type (${camera.type})
• ${context}/target/path: Invalid value (${channel.target.path
• ${context}/target/path: Could not find interpolation propert

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/04ce3aebfce02e04. Report an issue: GitHub.