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How to Resolve the "GET net::ERR_ABORTED 404 Not Found" Error in JavaScript

The GET net::ERR_ABORTED 404 (Not Found) error is one of the most common issues in web development. It's the browser's way of telling you: "I tried to fetch a resource (like a script, stylesheet, or image) for this webpage, but the server said that file doesn't exist at the requested URL."

This guide will walk you through a simple, step-by-step checklist to diagnose and fix the root cause of this error, which is always either a client-side path error or a server-side configuration error.

The Core Problem: A Mismatched Path​

At its heart, a 404 "Not Found" error means there is a mismatch between the URL your browser is requesting and the file path your server is looking for.

For example, your browser might request: http://localhost:3000/js/main.js

But your server might be looking for the file at: C:\MyProject\public\main.js

If the server's configuration doesn't correctly map that URL to that file path, it will return a 404 error.

Your Debugging Checklist​

Follow these steps in order to find the source of the mismatch.

This is the most common cause of the error. The src or href attribute in your HTML is pointing to the wrong location.

Example of code with errors:

<!-- This might be incorrect -->
<script src="/static/main.js"></script>
<link href="css/styles.css" rel="stylesheet">

Solution: Verify and Correct the Path

  1. Open the Network Tab: In your browser's developer tools (F12), go to the "Network" tab. Find the request that is failing (it will be red). The "Name" column will show you the exact path the browser is trying to access (e.g., /static/main.js).
  2. Check Your File Structure: Compare this requested path to the actual location of your file on your server.
  3. Try Different Path Formats:
    • Relative Path (from the HTML file): If your main.js is in a js folder next to your index.html, the path should be js/main.js. 
      <script src="js/main.js"></script>
    • Absolute Path (from the root of your web server): If you have configured your server to serve a public directory as the root, and your file is at public/js/main.js, the path should start with a /. 
      <script src="/js/main.js"></script>
    • Go Up One Level: If your file is in a parent directory, use ../. 
      <script src="../js/main.js"></script>
  4. Check for Typos: Ensure the filename and extension are spelled correctly.

Step 2: Check Your Server's Static File Configuration​

If you are sure your HTML path is correct, then the problem is likely on the server. Your server needs to be explicitly configured to serve "static assets" (like JS, CSS, and image files).

If this is not configured, the server will try to interpret a URL like /js/main.js as an API route, won't find a matching route, and will return a 404.

Problem: your browser requests http://localhost:3000/js/main.js, but your Express server doesn't know where to find the js folder.

Solution (Example with Express.js): you must use a "static middleware" to tell your server which directory contains your static files. In Express, this is express.static().

const express = require('express');
const path = require('path');
const app = express();

// This line tells Express to serve any files in the 'public' directory
// when a request is made.
// So, a request for '/js/main.js' will look for the file 'public/js/main.js'.
app.use(express.static('public'));

// It is a best practice to use an absolute path.
// This serves the 'public' folder located in the same directory as the server file.
app.use(express.static(path.join(__dirname, 'public')));


// Your other routes...
app.get('/', (req, res) => {
  res.sendFile(path.join(__dirname, 'public', 'index.html'));
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Every server framework (Nginx, Apache, Next.js, etc.) has its own way of configuring a static file directory. Consult the documentation for your specific server technology to ensure you have configured it correctly.

Conclusion​

The net::ERR_ABORTED 404 error is a straightforward problem with two possible sources.

  1. First, always check your client-side HTML. A typo or an incorrect relative/absolute path in a <script>, <link>, or <img> tag is the most common cause.
  2. If your HTML paths are correct, the problem is your server-side configuration. Ensure your server is correctly configured to serve static files from the appropriate directory.

By methodically checking these two points, you can quickly diagnose and fix any 404 "Not Found" error.

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