Скачать или смотреть Solving the Axios Network Error When Connecting to an Express Server from an Android Device

Discover effective solutions to resolve the Axios network error encountered when accessing a local Express server from an Android device.
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Tackling the Axios Network Error on Android Devices

When developing mobile applications with React Native and Expo, connecting to a local Express server can sometimes lead to frustrating issues, such as the dreaded AxiosError: Network Error. This is particularly common when transitioning from an emulator to a physical device. If you've found yourself facing this problem, you're not alone. In this post, we’ll explore the setup you might have and how to effectively troubleshoot and solve this network error.

Understanding the Setup

Before diving into solutions, let's first clarify the setup that leads to this problem:

Environment:

Device: An Android phone running the Expo app (after using eas build).

Server: An Express server running on a Macbook with an IP address of 192.168.1.44.

Request Configuration:

In your React Expo app, you make an Axios GET request to your server, like so:

[[See Video to Reveal this Text or Code Snippet]]

The BASE_URL is set to http://192.168.1.44:8000.

Successful Operations:

The application works properly while running in an emulator, meaning the local server is accessible on your development machine.

Common Challenges

When the same app is installed as an APK on an Android device, users often experience the following:

Axios Network Error: Despite correctly configuring the request, the physical device cannot communicate with the local server.

Persistent Logging: Even with the correct URL printed on the app, the problem persists.

Steps to Diagnose the Issue

From your own exploration and troubleshooting, it appears you've attempted a variety of checks:

Firewall Checks: Ensured that there are no firewalls blocking the Express server.

Request URL Verification: Confirmed the URL is indeed correct while running on the Android device.

Connectivity Testing: Verified successful communication between devices while using an emulator.

Given these, it's crucial to consider network restrictions that may apply when using physical devices.

Proposed Solution

After encountering this issue, a temporary workaround that has proven effective is using ngrok. This tool allows you to expose your local Express server to the public internet, enabling your mobile app to connect without the constraints of your local network.

Steps to Use ngrok

Install ngrok:

Download and install ngrok from the official website.

Run ngrok:

Open your terminal and start ngrok with the following command:

[[See Video to Reveal this Text or Code Snippet]]

This will generate a public URL that tunnels to your local Express server.

Update the BASE_URL:

Replace the BASE_URL in your React app with the public URL generated by ngrok.

Test the Application:

Deploy your updated app to your Android device and try the request again.

Benefits and Considerations

Using ngrok can be highly beneficial as it:

Eliminates Local Network Issues: By using a public URL, you bypass the local networking constraints that often arise with physical devices.

Quick and Easy: Setting up ngrok is quick, making it a valuable tool during development.

However, it's important to note that ngrok is not a long-term solution for production use due to potential security vulnerabilities. Always ensure you transition to a secured, properly set up environment for production applications.

Conclusion

Encounters with Axios Network Error can be a significant obstacle when developing mobile applications that rely on local servers. By understanding your setup and using tools like ngrok, you can circumvent common networking issues to ensure your app functions smoothly on physical devices. If you continue to experience difficulties, consider exploring network configurat