ERROR TypeError: _RNGestureHandlerModule.default.flushOperations is not a function (it is undefined), js engine: hermes

Understanding the Error

Error Description

The error “TypeError: _RNGestureHandlerModule.default.flushOperations is not a function (it is undefined), js engine: hermes” arises in React Native applications when using the `react-native-gesture-handler` library. This error signifies that the `flushOperations` method, which is essential for managing gesture events, cannot be found.

Causes

• Incorrect Installation or Linking: The `react-native-gesture-handler` library might not have been installed correctly or linked properly with your project.
• Conflicting Dependencies: Other libraries or packages within your project might be interfering with the gesture handler functionality.
• Version Mismatch: Outdated or incompatible versions of `react-native-gesture-handler`, React Native, or related libraries can lead to this issue.
• JavaScript Engine: The error specifically mentions the Hermes JavaScript engine, indicating that the issue might be related to Hermes-specific behaviors.

Troubleshooting and Solutions

Verify Installation and Linking

1. Install the Library: Ensure that `react-native-gesture-handler` is installed correctly using the following command:

   npm install react-native-gesture-handler

2. Link the Library: Properly link the library using the appropriate command for your platform:
   • iOS:

     cd ios && pod install

   • Android:

     npx react-native link react-native-gesture-handler

Update Dependencies

Upgrade `react-native-gesture-handler` and other related libraries to the latest compatible versions:

npm update react-native-gesture-handler

Resolve Conflicts

Review your project’s dependencies to identify potential conflicts with `react-native-gesture-handler`. Use tools like `npm ls` to inspect your dependency tree and address any issues.

Check Hermes Configuration

If you’re using the Hermes JavaScript engine, make sure it’s configured correctly in your project’s `android/app/build.gradle` file:

  defaultConfig {
    ...
    // Enable Hermes (only for Android)
    isEnableHermes = true
  }

React Native Version Compatibility

Ensure that the version of `react-native-gesture-handler` is compatible with your current React Native version. Refer to the library’s documentation for compatibility details.

Clean and Rebuild

Perform a clean build and rebuild of your project:

• Android:

  npx react-native start --reset-cache

• iOS:

  cd ios && pod deintegrate && pod install

Example Scenario

Suppose you have a React Native application with a simple gesture-based component:

import React from 'react';
import { View, Text, TouchableOpacity } from 'react-native';
import GestureHandler from 'react-native-gesture-handler';

const App = () => {
  const onTap = () => {
    console.log('Tapped!');
  };

  return (
    
      
        Tap Me!
      
    
  );
};

export default App;

After installing and linking the library, if you encounter the error, you can try the troubleshooting steps outlined above.

Conclusion

The error “TypeError: _RNGestureHandlerModule.default.flushOperations is not a function (it is undefined), js engine: hermes” in React Native is typically caused by issues related to installation, linking, dependencies, or compatibility. By following the troubleshooting and solutions described in this article, you can resolve the issue and effectively utilize gesture handling in your application.