Solving the Infamous “Error: Cannot find native module ‘ExpoPrint’, js engine: hermes” in React Native

Are you tired of staring at that pesky error message in your React Native project? You know the one: “Error: Cannot find native module ‘ExpoPrint’, js engine: hermes”. Don’t worry, friend, you’re not alone! Many developers have been where you are, and with this article, you’ll be up and running in no time.

What’s Causing the Error?

Before we dive into the solutions, let’s quickly discuss what’s causing this error. The “ExpoPrint” module is a native module provided by Expo, which allows you to print content from your React Native app. However, when you eject from Expo, this module becomes unavailable, leading to the dreaded error.

Why Hermes?

Hermes is a JavaScript engine developed by Facebook, designed to improve the performance and efficiency of JavaScript code. In React Native, Hermes is used as the default JavaScript engine. When you encounter this error, it’s likely because Hermes is unable to find the ExpoPrint module.

Solving the Error: Step-by-Step Guide

Now that we understand the cause, let’s get to the solution! Follow these steps to resolve the “Error: Cannot find native module ‘ExpoPrint’, js engine: hermes” in your React Native project:

Step 1: Install the React Native Print Module

First, you need to install the react-native-print module using npm or yarn:

npm install react-native-print

or

yarn add react-native-print

Step 2: Link the Module

Next, you need to link the module to your project:

npx react-native link react-native-print

This command will link the module to your project, making it available for use.

Step 3: Configure the Module

In your project’s Android directory (android/app/src/main/java/…), create a new file called `MainApplication.java`. Add the following code to this file:

import com.reactnative.print.PrintPackage;

public class MainApplication extends Application {
  private final ReactApplicationContext reactContext;

  public MainApplication(ReactApplicationContext reactContext) {
    super(reactContext);
    this.reactContext = reactContext;
  }

  @Override
  protected List<ReactPackage> getPackages() {
    return Arrays.<ReactPackage>asList(
      new MainReactPackage(),
      new PrintPackage()
    );
  }
}

This code configures the PrintPackage module for your project.

Step 4: Add the Print Functionality

Finally, you need to add the print functionality to your React Native component. Create a new JavaScript file, for example, `Print.js`, and add the following code:

import React, { useState } from 'react';
import { View, Text, Button } from 'react-native';
import { print } from 'react-native-print';

const PrintScreen = () => {
  const [printed, setPrinted] = useState(false);

  const handlePrint = async () => {
    try {
      await print({
        html: '<h1>Hello, World!</h1>',
      });
      setPrinted(true);
    } catch (error) {
      console.error(error);
    }
  };

  return (
    <View>
      <Text>Print Example</Text>
      <Button title="Print" onPress={handlePrint} />
      {printed ? <Text>Printed successfully!</Text> : null}
    </View>
  );
};

export default PrintScreen;

This code creates a basic print functionality using the react-native-print module.

Troubleshooting Common Issues

While following these steps should resolve the “Error: Cannot find native module ‘ExpoPrint’, js engine: hermes” issue, you might encounter some common problems. Here are some troubleshooting tips to help you overcome them:

Error: Unable to find module

If you encounter an error saying “Unable to find module react-native-print”, make sure you’ve installed the module correctly using npm or yarn. Check your `package.json` file to ensure the module is listed as a dependency.

Error: Unable to link module

If you encounter an error while linking the module, try deleting the `node_modules` directory and running `npm install` or `yarn install` again. This should re-link the module correctly.

Error: Print functionality not working

If the print functionality isn’t working as expected, check your device’s print settings to ensure that printing is enabled. Also, make sure you’ve added the necessary permissions to your `AndroidManifest.xml` file.

Conclusion

Congratulations! You’ve successfully resolved the “Error: Cannot find native module ‘ExpoPrint’, js engine: hermes” issue in your React Native project. By following these step-by-step instructions, you should now be able to use the react-native-print module to print content from your app.

Remember, if you encounter any issues, refer to the troubleshooting section or seek help from the React Native community. Happy coding!

Module	Description
ExpoPrint	A native module provided by Expo for printing content.
React Native Print	A module for printing content in React Native.
Hermes	A JavaScript engine developed by Facebook for improving performance and efficiency.

1. Install the react-native-print module using npm or yarn.
2. Link the module to your project using the `react-native link` command.
3. Configure the module in your project’s Android directory.
4. Add the print functionality to your React Native component.

• Error: Unable to find module react-native-print
• Error: Unable to link module
• Error: Print functionality not working

Frequently Asked Question

Stuck with the error “Cannot find native module ‘ExpoPrint’, js engine: hermes” in React Native? Don’t worry, we’ve got you covered! Here are the top 5 questions and answers to help you troubleshoot and solve this frustrating issue.