libc++abi: terminating due to uncaught exception of type facebook::jsi::JSINativeException: Compiling JS failed: 1:1:invalid empty parentheses '( )'

[atharshafi]

1. I tap Detect Face (which sets showCamera = true).
2. The camera preview opens using react-native-vision-camera.
3. All buttons in the overlay stop responding — including the Cancel button.
4. I check the logs and see the following crash:

libc++abi: terminating due to uncaught exception of type facebook::jsi::JSINativeException: Compiling JS failed: 1:1:invalid empty parentheses '( )'

I suspect the crash is related to how the frameProcessor function is handled.
The error Compiling JS failed: 1:1: invalid empty parentheses '( )' suggests that the 'worklet' directive inside useFrameProcessor() is not being compiled correctly.

My frameProcessor uses 'worklet' and runOnJS() like this:

//frameProcessor code

// Face detection callback
const updateFaceDetection = Worklets.createRunOnJS((detected: boolean) => {
setFaceDetected(detected);
});

// Frame processor
const frameProcessor = useFrameProcessor((frame) => {
'worklet';
try {
const faces = detectFaces(frame);
updateFaceDetection(faces.length > 0);
} catch (error) {
updateFaceDetection(false);
}
}, []);

Full build logs

INFO: Created TensorFlow Lite XNNPACK delegate for CPU.
14:43:19.764: [info] 📸 VisionCamera.didSetProps(_:): Updating 23 props: [onInitialized, cameraId, position, enableBufferCompression, preview, onStarted, onCodeScanned, top, onOutputOrientationChanged, right, isActive, isMirrored, onViewReady, onError, onStopped, onPreviewOrientationChanged, onPreviewStarted, enableFrameProcessor, onPreviewStopped, left, bottom, photo, onShutter]
14:43:19.766: [info] 📸 VisionCamera.configurePreviewOrientation(_:): Updating Preview rotation: portrait...
14:43:19.766: [info] 📸 VisionCamera.configureOutputOrientation(_:): Updating Outputs rotation: portrait...
14:43:19.767: [info] 📸 VisionCamera.configure(_:): configure { ... }: Waiting for lock...
14:43:19.770: [info] 📸 VisionCamera.configure(_:): configure { ... }: Updating CameraSession Configuration... Difference(inputChanged: true, outputsChanged: true, videoStabilizationChanged: true, orientationChanged: true, formatChanged: true, sidePropsChanged: true, torchChanged: true, zoomChanged: true, exposureChanged: true, audioSessionChanged: true, locationChanged: true)
14:43:19.770: [info] 📸 VisionCamera.configureDevice(configuration:): Configuring Input Device...
14:43:19.770: [info] 📸 VisionCamera.configureDevice(configuration:): Configuring Camera com.apple.avfoundation.avcapturedevice.built-in_video:1...
14:43:19.772: [info] 📸 VisionCamera.configureDevice(configuration:): Successfully configured Input Device!
14:43:19.772: [info] 📸 VisionCamera.configureOutputs(configuration:): Configuring Outputs...
14:43:19.772: [info] 📸 VisionCamera.configureOutputs(configuration:): Adding Photo output...
14:43:19.774: [info] 📸 VisionCamera.configureOutputs(configuration:): Adding Video Data output...
14:43:19.775: [info] 📸 VisionCamera.configureOutputs(configuration:): AVCaptureVideoDataOutput will rotate Frames to landscapeRight...
14:43:19.775: [info] 📸 VisionCamera.configurePreviewOrientation(_:): Updating Preview rotation: portrait...
14:43:19.775: [info] 📸 VisionCamera.configureOutputOrientation(_:): Updating Outputs rotation: portrait...
14:43:19.775: [info] 📸 VisionCamera.configureOutputs(configuration:): Successfully configured all outputs!
14:43:19.776: [info] 📸 VisionCamera.setTargetOutputOrientation(_:): Setting target output orientation from device to device...
14:43:19.777: [info] 📸 VisionCamera.getPixelFormat(for:): Available Pixel Formats: ["420v", "420f", "BGRA", "&8v0", "-8v0", "&8f0", "-8f0", "&BGA", "-BGA"], finding best match... (pixelFormat="yuv", enableHdr={false}, enableBufferCompression={false})
14:43:19.777: [info] 📸 VisionCamera.getPixelFormat(for:): Using PixelFormat: 420f...
14:43:20.259: [info] 📸 VisionCamera.init(frame:session:): Preview Layer started previewing.
14:43:20.260: [info] 📸 VisionCamera.configure(_:): Beginning AudioSession configuration...
14:43:20.260: [info] 📸 VisionCamera.configureAudioSession(configuration:): Configuring Audio Session...
14:43:20.261: [info] 📸 VisionCamera.configure(_:): Committed AudioSession configuration!
14:43:20.263: [info] 📸 VisionCamera.configure(_:): Beginning Location Output configuration...
libc++abi: terminating due to uncaught exception of type facebook::jsi::JSINativeException: Compiling JS failed: 1:1:invalid empty parentheses '( )'

Project dependencies

{
  "name": "MyApp",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "android": "react-native run-android",
    "ios": "react-native run-ios",
    "lint": "eslint .",
    "start": "react-native start",
    "test": "jest"
  },
  "dependencies": {
    "@aws-amplify/react-native": "^1.1.10",
    "@react-native-async-storage/async-storage": "^2.1.2",
    "@react-native-community/datetimepicker": "^8.4.1",
    "@react-native-community/geolocation": "^3.4.0",
    "@react-native-community/netinfo": "^11.4.1",
    "@react-native-picker/picker": "^2.11.0",
    "@react-navigation/drawer": "^7.3.12",
    "@react-navigation/native": "^7.1.9",
    "@react-navigation/stack": "^7.3.2",
    "aws-amplify": "^6.15.0",
    "axios": "^1.9.0",
    "geolib": "^3.3.4",
    "haversine": "^1.1.1",
    "install": "^0.13.0",
    "moment": "^2.30.1",
    "npm": "^11.4.2",
    "react": "19.0.0",
    "react-native": "0.79.2",
    "react-native-camera": "^4.2.1",
    "react-native-circular-progress": "^1.4.1",
    "react-native-country-picker-modal": "^2.0.0",
    "react-native-dropdown-picker": "^5.4.6",
    "react-native-exception-handler": "^2.10.10",
    "react-native-geocoding": "^0.5.0",
    "react-native-geolocation-service": "5.3.1",
    "react-native-gesture-handler": "^2.25.0",
    "react-native-image-crop-picker": "^0.42.0",
    "react-native-keyboard-aware-scroll-view": "^0.9.5",
    "react-native-linear-gradient": "^2.8.3",
    "react-native-maps": "^1.23.8",
    "react-native-material-tabs": "^4.2.0",
    "react-native-modalize": "^2.1.1",
    "react-native-paper": "^5.14.5",
    "react-native-permissions": "^5.4.0",
    "react-native-progress": "^5.0.1",
    "react-native-reanimated": "^3.17.5",
    "react-native-restart": "^0.0.27",
    "react-native-safe-area-context": "^5.4.1",
    "react-native-segmented-control-tab": "^4.0.0",
    "react-native-simple-toast": "^3.3.2",
    "react-native-svg": "^15.12.0",
    "react-native-uuid-generator": "^6.1.1",
    "react-native-vector-icons": "^10.2.0",
    "react-native-vision-camera": "^4.7.0",
    "react-native-vision-camera-face-detector": "^1.8.6",
    "react-native-worklets-core": "^1.6.0",
    "react-redux": "^9.2.0",
    "redux": "^5.0.1",
    "redux-persist": "^6.0.0",
    "redux-saga": "^1.1.3",
    "reduxsauce": "^2.0.0"
  },
  "devDependencies": {
    "@babel/core": "^7.25.2",
    "@babel/preset-env": "^7.25.3",
    "@babel/preset-typescript": "^7.27.1",
    "@babel/runtime": "^7.25.0",
    "@react-native-community/cli": "18.0.0",
    "@react-native-community/cli-platform-android": "18.0.0",
    "@react-native-community/cli-platform-ios": "18.0.0",
    "@react-native/babel-preset": "^0.79.2",
    "@react-native/eslint-config": "0.79.2",
    "@react-native/metro-config": "0.79.2",
    "@react-native/typescript-config": "0.79.2",
    "@types/jest": "^29.5.13",
    "@types/react": "^19.1.6",
    "@types/react-native": "^0.72.8",
    "@types/react-test-renderer": "^19.0.0",
    "babel-plugin-module-resolver": "^5.0.2",
    "eslint": "^8.19.0",
    "jest": "^29.6.3",
    "prettier": "2.8.8",
    "react-test-renderer": "19.0.0",
    "typescript": "^5.0.4"
  },
  "engines": {
    "node": ">=18"
  },
}

VisionCamera Version

4.7.0

Target platforms

iOS

Operating system

MacOS

Can you build the VisionCamera Example app?

I didn't try (⚠️ your issue might get ignored & closed if you don't try this)

Additional information

• I am using Expo
• I have enabled Frame Processors (react-native-worklets-core)
• I have read the Troubleshooting Guide
• I agree to follow this project's Code of Conduct
• I searched for similar issues in this repository and found none.

[maintenance-hans]

Guten Tag, Hans here! 🍻 It looks like you have a well-written issue, and you've provided relevant information for us to investigate. The error you're encountering, Compiling JS failed: 1:1: invalid empty parentheses '( )', often indicates that there's a problem with your worklet implementation or how it's being used.

Please ensure that your worklet is defined properly, and check that you are following the documentation for using frame processors. It might help to simplify your processor function for debugging purposes or try running the VisionCamera example app to see if the issue persists there.

If you continue facing this problem, please provide additional logs from Xcode so we can have more insight into what's happening. You can collect logs by using the console in Xcode during the build or runtime.

Feel free to ask more questions if you need help!

Note: If you think I made a mistake, please ping @mrousavy to take a look.

[atharshafi]

This is my full code

import {
StyleSheet,
Text,
View
} from 'react-native'
import {
useEffect,
useState,
useRef
} from 'react'
import {
Camera,
runAsync,
useCameraDevice,
useFrameProcessor
} from 'react-native-vision-camera'
import {
Face,
useFaceDetector,
FaceDetectionOptions
} from 'react-native-vision-camera-face-detector'
import { Worklets } from 'react-native-worklets-core'

export default function App() {
const faceDetectionOptions = useRef( {
// detection options
} ).current

const device = useCameraDevice('front')
const { detectFaces } = useFaceDetector( faceDetectionOptions )

useEffect(() => {
(async () => {
const status = await Camera.requestCameraPermission()
console.log({ status })
})()
}, [device])

const handleDetectedFaces = Worklets.createRunOnJS( (
faces: Face[]
) => {
console.log( 'faces detected', faces )
})

const frameProcessor = useFrameProcessor((frame) => {
'worklet'
runAsync(frame, () => {
'worklet'
const faces = detectFaces(frame)
// ... chain some asynchronous frame processor
// ... do something asynchronously with frame
handleDetectedFaces(faces)
})
// ... chain frame processors
// ... do something with frame
}, [handleDetectedFaces])

return (
<View style={{ flex: 1 }}>
{!!device? :
No Device
}

)
}