{"record":{"id":"27ea676f846f43db","repo":"BabylonJS/Babylon.js","slug":"invalid-property-this-targetpath-in-property","errorCode":null,"errorMessage":"Invalid property (${this._targetPath}) in property path (${targetPropertyPath.join(\".\")})","messagePattern":"Invalid property \\((.+?)\\) in property path \\((.+?)\\)","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/dev/core/src/Animations/runtimeAnimation.ts","lineNumber":262,"sourceCode":"        if (targetPropertyPath.length > 1) {\r\n            let property = target;\r\n            for (let index = 0; index < targetPropertyPath.length - 1; index++) {\r\n                const name = targetPropertyPath[index];\r\n                property = property[name];\r\n                if (property === undefined) {\r\n                    throw new Error(`Invalid property (${name}) in property path (${targetPropertyPath.join(\".\")})`);\r\n                }\r\n            }\r\n\r\n            this._targetPath = targetPropertyPath[targetPropertyPath.length - 1];\r\n            this._activeTargets[targetIndex] = property;\r\n        } else {\r\n            this._targetPath = targetPropertyPath[0];\r\n            this._activeTargets[targetIndex] = target;\r\n        }\r\n\r\n        if (this._activeTargets[targetIndex][this._targetPath] === undefined) {\r\n            throw new Error(`Invalid property (${this._targetPath}) in property path (${targetPropertyPath.join(\".\")})`);\r\n        }\r\n    }\r\n\r\n    /**\r\n     * Gets the animation from the runtime animation\r\n     */\r\n    public get animation(): Animation {\r\n        return this._animation;\r\n    }\r\n\r\n    /**\r\n     * Resets the runtime animation to the beginning\r\n     * @param restoreOriginal defines whether to restore the target property to the original value\r\n     */\r\n    public reset(restoreOriginal = false): void {\r\n        if (restoreOriginal) {\r\n            if (this._target instanceof Array) {\r\n                let index = 0;\r","sourceCodeStart":244,"sourceCodeEnd":280,"githubUrl":"https://github.com/BabylonJS/Babylon.js/blob/0592b347b8a4ee0236089ea86a749cacfdb266d8/packages/dev/core/src/Animations/runtimeAnimation.ts#L244-L280","documentation":"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.","triggerScenarios":"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).","commonSituations":"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.","solutions":["Initialize the property on the target before animating (e.g. mesh.rotationQuaternion = Quaternion.Identity())","Correct the targetProperty string to an existing property","Verify the property type matches the animation type (float vs Vector3 vs Quaternion)","Use scene.getProperty or direct access to check the property exists before beginAnimation"],"exampleFix":"// before\nscene.beginDirectAnimation(mesh, quatAnim, 0, 60, true); // mesh.rotationQuaternion undefined\n// after\nmesh.rotationQuaternion = mesh.rotationQuaternion ?? Quaternion.Identity();\nscene.beginDirectAnimation(mesh, quatAnim, 0, 60, true);","handlingStrategy":"validation","validationCode":"if ((mesh as any)[animation.targetProperty] === undefined) {\n    console.warn(`Target ${mesh.name} has no property '${animation.targetProperty}'`);\n} else {\n    scene.beginAnimation(mesh, 0, 100);\n}","typeGuard":null,"tryCatchPattern":"try {\n    scene.beginAnimation(target, 0, 60, true);\n} catch (e) {\n    if (e.message.includes(\"Invalid property\")) {\n        // initialize missing property then retry once\n        (target as any)[extractPath(e)] = defaultValue;\n        scene.beginAnimation(target, 0, 60, true);\n    }\n}","preventionTips":["Initialize animated properties (rotationQuaternion, custom scalars) before animating","Keep animation targetProperty strings in constants to avoid typos","Check property type matches the Animation's dataType (float/Vector3/Quaternion)"],"tags":["animation","property-path","validation"],"backgroundTag":"invalid-property-path","analyzedSha":"0592b347b8a4ee0236089ea86a749cacfdb266d8","analyzedAt":"2026-08-30T15:11:20.442Z","schemaVersion":2},"datasetVersion":"2026-08-30T18:17:15.746Z"}