How to Solve the `404 Not Found` Error in React-Redux with Code Examples Using Process ENV and Authentication for User`s API

Table of content

  1. Introduction
  2. Understanding the '404 Not Found' Error in React-Redux
  3. Ways to Solve the '404 Not Found' Error
  4. Code Examples Using Process ENV and Authentication for User's API
  5. Conclusion
  6. References
  7. Glossary
  8. Appendices


The internet loves to throw us curveballs, and one of the most frustrating ones is the '404 Not Found' error. This error means that the server cannot find the requested data or page and returns a blank screen or a message saying "404 Not Found." While this error can occur on any website or application, it's particularly common in React-Redux projects, where API calls are a critical part of data management.

In this article, we'll explore different ways to tackle this error in React-Redux. We'll use common practices such as process.env, authentication, and error handling to get our application back on track. We'll also provide code examples to make it easier to follow and understand.

Even though programming can be daunting, it's essential to understand it in today's world. It's responsible for powering the technology we use every day, from basic apps to complex systems that run multinational corporations. By mastering the fundamentals, we can build and maintain reliable, efficient, and secure applications. So let's dive in and learn how to solve the '404 Not Found' error in React-Redux!

Understanding the ‘404 Not Found’ Error in React-Redux

The '404 Not Found' Error is one of the most common errors encountered by developers when working with React-Redux applications. As the name suggests, this error occurs when the server is unable to find the requested resource (usually a web page or API endpoint) on the server.

This error can occur for a variety of reasons, including typos in the URL, missing files or directories on the server, or authentication issues. It can be frustrating for users and developers alike, as it often brings the application to a complete halt. However, understanding the root cause of the error can help developers quickly troubleshoot and fix the issue.

One common cause of the '404 Not Found' Error is authentication issues. When working with user data in React-Redux applications, it is important to ensure that users are properly authenticated before accessing sensitive data or resources. This can be achieved using process ENV, which allows developers to securely store and manage environment variables in their applications.

Another potential cause of this error is invalid or outdated API endpoints. In order to prevent this, developers should regularly update their applications to ensure that all API endpoints are up-to-date and functioning properly. Additionally, proper error handling techniques can help prevent these errors from occurring in the first place.

Overall, understanding the '404 Not Found' Error is crucial for developers working with React-Redux applications. By implementing proper authentication techniques and regularly updating their applications, developers can help prevent this error from occurring and ensure a seamless user experience.

Ways to Solve the ‘404 Not Found’ Error

There are a few different ways that you can solve the '404 Not Found' error in React-Redux. One common approach is to use process.env to define the base URL for your API calls. This can help ensure that your requests are being sent to the right place, and can prevent misunderstandings between your frontend and backend code.

Another important step in preventing the '404 Not Found' error is to make sure that you are using authentication when accessing user-sensitive data. This can help protect against unauthorized access and prevent data breaches. By requiring users to log in before accessing certain pages or features, you can ensure that only approved users are able to access sensitive data.

Finally, it's important to check your code for any typos or errors that might be causing the '404 Not Found' error. This can be done by carefully reviewing your code line by line, or by using a debugging tool to help identify the problem. By taking the time to carefully review your code and troubleshoot any errors, you can reduce the likelihood of encountering the '404 Not Found' error in the future.

Overall, there are a number of different steps that you can take to solve the '404 Not Found' error in React-Redux. Whether you are using process.env to define your base URL, implementing authentication to protect user data, or simply reviewing your code for errors, there are many strategies you can use to ensure that your code is working properly and effectively communicating with your backend server.

Code Examples Using Process ENV and Authentication for User’s API

Using process ENV and authentication can solve the "404 Not Found" error in React-Redux. Here's an example of how to implement this approach for a user's API:

First, create a process ENV variable to store the API URL. This can be done in the ".env" file:


Then, in your code, import the process ENV variable:

import { REACT_APP_API_URL } from '../.env';

Next, use this variable to create the API URL:

const API_URL = `${REACT_APP_API_URL}/users`;

Now, let's add authentication to the request headers to ensure the API can be accessed by authorized users only. Here's an example using JWT (JSON Web Tokens) authentication:

const token = getToken(); // getToken is a function that retrieves the user's JWT
const headers = {
  Authorization: `Bearer ${token}`,
  'Content-Type': 'application/json',

Finally, make sure to use the API URL and headers when making API requests:

axios.get(`${API_URL}/123`, { headers })
  .then((response) => {
  .catch((error) => {

With these steps, the "404 Not Found" error should be resolved, and API requests will be secure and authenticated. Remember to handle errors effectively, as shown in the example above. This strategy can be applied to other APIs and programming languages, providing a secure and efficient way to use APIs in your projects.


In , the '404 Not Found' error is a common issue that programmers face when working with React-Redux applications. By using Process ENV and authentication for User's API, developers can solve this error efficiently.

It is important to note that understanding the fundamentals of programming is crucial for solving this and many other errors. Taking the time to learn the basics of programming and familiarizing oneself with various programming languages and frameworks can help programmers avoid common errors and troubleshoot issues more effectively.

In addition, learning from the mistakes of other developers is an excellent way to improve one's programming skills. By keeping up-to-date with industry trends and best practices, programmers can stay current with the latest technologies and techniques and stay ahead of the curve.

Overall, solving the '404 Not Found' error requires a combination of problem-solving skills, attention to detail, and knowledge of programming fundamentals. By following the steps outlined in this article, programmers can overcome this error and deliver high-quality, successful applications to their clients and users.


If you want to learn more about solving the '404 Not Found' Error in React-Redux, there are many resources available online. Here are a few articles that could be helpful:

Remember, programming is a constantly evolving field, and there will always be new tools, techniques, and resources available. By staying curious and seeking out information, you can continue to improve your programming skills and solve the challenges that come with building complex apps.


Here are some common terms and concepts related to React-Redux that you may encounter in your journey as a developer.

404 Not Found: This error message is displayed by a web server when it cannot find the requested resource. In the context of React-Redux, it often indicates that there is a problem with the application's routing or API calls.

Process ENV: This is short for "process environment variables," which are global variables that can be accessed by a running process, such as a Node.js server. They are commonly used to store sensitive information, such as API keys or database credentials, that should not be hard-coded into an application's source code.

Authentication: This refers to the process of identifying and verifying the identity of a user or system. In the context of web development, it typically involves requiring users to log in with a username and password or other credentials, in order to access restricted parts of a site or application.

API: Short for "Application Programming Interface," an API is a set of protocols, functions, and definitions that allows different software systems to communicate and interact with each other. APIs are commonly used to retrieve or send data from a remote server, such as retrieving user information or updating a database.

By familiarizing yourself with these terms and concepts, you will be better equipped to understand and troubleshoot issues that may arise in your React-Redux projects.


In this section, we provide additional resources for readers who want to learn more about the concepts and tools mentioned in this article.

Additional Resources

Code Examples

Here are some sample code snippets that illustrate how to solve the 404 Not Found error in React-Redux with Process ENV and JWT authentication.

import axios from 'axios';

const API_URL = process.env.REACT_APP_API_URL; // Use .env file to store API URL

const getUserData = async (userId, token) => {
  try {
    const response = await axios.get(`${API_URL}/users/${userId}`, {
      headers: { Authorization: `Bearer ${token}` },
  } catch (error) {
const login = async (email, password) => {
  try {
    const response = await fetch(`${API_URL}/auth/login`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ email, password }),
    const data = await response.json();
    return data.token;
  } catch (error) {
const authMiddleware = (store) => (next) => (action) => {
  const { type, payload } = action;
  const { isAuthenticated, token } = store.getState().auth;

  if (type === 'LOGIN_SUCCESS') {
    localStorage.setItem('token', payload.token);

  if (type === 'LOGOUT_SUCCESS') {
    delete axios.defaults.headers.common.Authorization;

  if (isAuthenticated && token) {
    axios.defaults.headers.common.Authorization = `Bearer ${token}`;



We hope this article has helped you better understand how to solve the 404 Not Found error in React-Redux with Process ENV and JWT authentication. By using these tools and techniques, you can build more secure and reliable applications that provide a better user experience. Remember to always keep learning and experimenting with new technologies to stay ahead in the ever-evolving world of programming.

As an experienced software engineer, I have a strong background in the financial services industry. Throughout my career, I have honed my skills in a variety of areas, including public speaking, HTML, JavaScript, leadership, and React.js. My passion for software engineering stems from a desire to create innovative solutions that make a positive impact on the world. I hold a Bachelor of Technology in IT from Sri Ramakrishna Engineering College, which has provided me with a solid foundation in software engineering principles and practices. I am constantly seeking to expand my knowledge and stay up-to-date with the latest technologies in the field. In addition to my technical skills, I am a skilled public speaker and have a talent for presenting complex ideas in a clear and engaging manner. I believe that effective communication is essential to successful software engineering, and I strive to maintain open lines of communication with my team and clients.
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