BabylonJS/Babylon.js · error · Error

Invalid property (${name}) in property path (${targetPropert

Error message

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

What it means

RuntimeAnimation._preparePath resolves multi-segment property paths like 'position.x' by walking intermediate properties on the target. If any intermediate property is undefined at its index, the path is invalid for animation and this error is thrown.

Source

Thrown at packages/dev/core/src/Animations/runtimeAnimation.ts:250

        if (events && events.length > 0) {
            for (const e of events) {
                this._events.push(e._clone());
            }
        }

        this._enableBlending = target && target.animationPropertiesOverride ? target.animationPropertiesOverride.enableBlending : this._animation.enableBlending;
    }

    private _preparePath(target: any, targetIndex = 0) {
        const targetPropertyPath = this._animation.targetPropertyPath;

        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
     */

View on GitHub (pinned to 0592b347b8)

Solutions

1. Fix the targetPropertyPath to match the actual object structure
2. Verify each intermediate property exists on the target before beginAnimation
3. Log the target object and confirm the property chain at runtime
4. Guard with typeof checks or optional setup before starting the animation

Example fix

// before
scene.beginAnimation(mesh, 0, 100, true); // animation targets "postion.x" (typo)
// after
// fix path in the Animation:
new Animation("a", "position.x", 30, ANIMATIONTYPE_FLOAT, ANIMATIONLOOPMODE_CYCLE);

function canAnimatePath(target: any, path: string[]): boolean {
    let obj = target;
    for (let i = 0; i < path.length - 1; i++) {
        if (obj == null || obj[path[i]] === undefined) return false;
        obj = obj[path[i]];
    }
    return obj != null && obj[path[path.length - 1]] !== undefined;
}
// before beginAnimation:
if (!canAnimatePath(mesh, animation.targetPropertyPath)) { ... }

try {
    scene.beginAnimation(mesh, 0, 100, true);
} catch (e) {
    if (e.message.includes("Invalid property")) {
        console.error("Bad animation path:", e.message, "on target", mesh?.name);
    }
}

When it happens

Trigger: Creating a new RuntimeAnimation (via scene.beginAnimation / beginDirectAnimation) whose targetPropertyPath contains an intermediate property that does not exist on the target, e.g. animating 'foo.bar' on an object with no 'foo'.

Common situations: Typos in animation target property paths; animating a property on a mesh whose sub-object was renamed (e.g. 'renderingGroupId' vs actual); targets that are null or shaped differently than expected; GLTF-loaded nodes with different hierarchies.

Related errors

• Invalid property (${this._targetPath}) in property path (${t
• 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/96d4cb64ba69f380. Report an issue: GitHub.