Resolving Webpack Dev Server HMR Update Errors

Learn how to fix the common issue of Webpack Dev Server showing `[HMR] Update failed: Error: Failed to fetch update manifest Internal Server Error` by ensuring proper configuration and HTML integration.
---
This video is based on the question https://stackoverflow.com/q/67131863/ asked by the user 'Darren Smith' ( https://stackoverflow.com/u/10957551/ ) and on the answer https://stackoverflow.com/a/67132593/ provided by the user 'Darren Smith' ( https://stackoverflow.com/u/10957551/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Webpack Dev Server: [HMR] Update failed: Error: Failed to fetch update manifest Internal Server Error

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving Webpack Dev Server HMR Update Errors: A Comprehensive Guide

If you're a web developer dabbling in JavaScript, Node.js, and Webpack, you might have encountered a rather frustrating error during Hot Module Replacement (HMR) – "[HMR] Update failed: Error: Failed to fetch update manifest Internal Server Error." This error often appears when you're trying to live reload after making changes to your code. If you've been scratching your head over this issue, you're not alone!

In this guide, we will delve into the underlying causes of this error and explore effective steps for resolving it. We'll break down the necessary configurations and provide guidance on integrating your bundled JavaScript file correctly. Let’s get started!

Understanding the Problem

When the Webpack Dev Server is running, it needs to fetch updated modules automatically from the server. If there’s a misconfiguration, you might encounter the HMR error, which interrupts your development workflow. Below are some common indicators of this issue:

The browser console displays the HMR error message after saving a file change.

Live reload does not function correctly, leaving you stuck with outdated content in your browser.

An Example Scenario

Consider a simple React application set up to run on port 8000. If your files aren't being fetched correctly – even after configuring HMR – this could lead to the aforementioned error message. Sometimes, setting writeToDisk: true could temporarily remedy the issue by writing updates to the disk; however, this is not an optimal solution as it fills up your source directory.

Steps to Solve the Issue

Update Webpack Configuration

The resolution often lies in ensuring that the bundled JavaScript file is correctly referenced in your HTML file on the same port that the Webpack Dev Server is running. Here’s how to update your Webpack configuration:

Set the correct output settings in your Webpack config:

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

Ensure that you reference the correct script source in your HTML:

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

This setup ensures that the Webpack Dev Server can serve the updated modules on the same port (8080) that the HTML file is referencing.

Conclusion

By ensuring your Webpack configuration and HTML references are correctly aligned, you can resolve the frustrating HMR update issues. This simple adjustment can significantly streamline your development experience, allowing you to take advantage of Webpack’s hot reloading capabilities without a hitch.

Hopefully, these insights and solutions will help you or someone you know avoid the pitfalls of HMR errors in Webpack. Keep coding, and happy developing!