BabylonJS/Babylon.js · error · Error

Invalid property (${this._targetPath}) in property path (${t

Error message

Invalid property (${this._targetPath}) in property path (${targetPropertyPath.join(".")})

What it means

After resolving the path, _preparePath checks that the final target property (this._targetPath) exists on the resolved target. If target[path] === undefined, the animation cannot read/write the property, so this error is thrown.

Source

Thrown at packages/dev/core/src/Animations/runtimeAnimation.ts:262

        if (targetPropertyPath.length > 1) {
            let property = target;
            for (let index = 0; index < targetPropertyPath.length - 1; index++) {
                const name = targetPropertyPath[index];
                property = property[name];
                if (property === undefined) {
                    throw new Error(`Invalid property (${name}) in property path (${targetPropertyPath.join(".")})`);
                }
            }

            this._targetPath = targetPropertyPath[targetPropertyPath.length - 1];
            this._activeTargets[targetIndex] = property;
        } else {
            this._targetPath = targetPropertyPath[0];
            this._activeTargets[targetIndex] = target;
        }

        if (this._activeTargets[targetIndex][this._targetPath] === undefined) {
            throw new Error(`Invalid property (${this._targetPath}) in property path (${targetPropertyPath.join(".")})`);
        }
    }

    /**
     * Gets the animation from the runtime animation
     */
    public get animation(): Animation {
        return this._animation;
    }

    /**
     * Resets the runtime animation to the beginning
     * @param restoreOriginal defines whether to restore the target property to the original value
     */
    public reset(restoreOriginal = false): void {
        if (restoreOriginal) {
            if (this._target instanceof Array) {
                let index = 0;

View on GitHub (pinned to 0592b347b8)

Solutions

1. Initialize the property on the target before animating (e.g. mesh.rotationQuaternion = Quaternion.Identity())
2. Correct the targetProperty string to an existing property
3. Verify the property type matches the animation type (float vs Vector3 vs Quaternion)
4. Use scene.getProperty or direct access to check the property exists before beginAnimation

Example fix

// before
scene.beginDirectAnimation(mesh, quatAnim, 0, 60, true); // mesh.rotationQuaternion undefined
// after
mesh.rotationQuaternion = mesh.rotationQuaternion ?? Quaternion.Identity();
scene.beginDirectAnimation(mesh, quatAnim, 0, 60, true);

if ((mesh as any)[animation.targetProperty] === undefined) {
    console.warn(`Target ${mesh.name} has no property '${animation.targetProperty}'`);
} else {
    scene.beginAnimation(mesh, 0, 100);
}

try {
    scene.beginAnimation(target, 0, 60, true);
} catch (e) {
    if (e.message.includes("Invalid property")) {
        // initialize missing property then retry once
        (target as any)[extractPath(e)] = defaultValue;
        scene.beginAnimation(target, 0, 60, true);
    }
}

When it happens

Trigger: beginAnimation with an Animation whose targetProperty does not exist on the target object, e.g. animating 'rotationQuaternion' on a mesh where it is undefined (only 'rotation' exists), or single-segment paths like 'scal' (typo).

Common situations: Animating rotationQuaternion on meshes that use Euler rotation; typos in targetProperty; animating custom properties never initialized on the target (undefined rather than a number); API changes between Babylon versions.

Related errors

• Invalid property (${name}) in property path (${targetPropert
• step size should be less than 1.
• Invalid or empty skeleton provided
• Sample2DRgbaToRef: widthPx and heightPx must be positive.
• At least one mesh is needed to create the nav mesh.

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/27ea676f846f43db. Report an issue: GitHub.