Resolving the 404 Error in Your Spring Boot Application on the Server

Discover how to troubleshoot and fix the `404 Error` in your Spring Boot application when deployed on a server. This comprehensive guide covers the potential causes and solutions for your issue.
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Resolving the 404 Error in Your Spring Boot Application on the Server: A Step-by-Step Guide

Deploying a Spring Boot application to a server often raises unexpected issues, especially when everything works perfectly on your local machine. One common challenge developers face is receiving a 404 Error upon deployment. This guide addresses the potential causes of this error and guides you through the corrective steps to resolve it.

Understanding the 404 Error

A 404 Error indicates that the requested resource could not be found on the server. When this occurs, it means that the application is running, but the URLs or endpoints you are trying to access are not being recognized. Here are a few scenarios where this issue commonly arises in Spring Boot applications:

Missing or incorrect routing configuration

Incorrectly mapped controllers

Misconfigured application properties

Deployment issues related to the server environment

In this guide, we will focus primarily on improper configuration of the application properties and controller annotations, which can lead to a 404 error.

Troubleshooting Steps to Fix the 404 Error

Follow the steps below to diagnose and rectify the issues causing the 404 Error in your Spring Boot application.

Step 1: Verify Controller Annotations

Make sure to use the correct annotations on your controllers. Often developers mistakenly use -RestController, which is appropriate for API controllers that return JSON responses. However, if your intention is to return a view (like an HTML page), you should utilize the -Controller annotation instead.

Example of Changing -RestController to -Controller

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Step 2: Check the Application Properties

Misconfigured application properties can also lead to connection issues, which might be interpreted as a not found error. It’s essential to ensure these properties are correctly set up. Pay close attention to your database connection settings.

Here’s an example of how to configure your application.properties file correctly:

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Adjust the database connection details: Make sure you replace <your_database_name>, <your_username>, and <your_password> with your actual database credentials.

Step 3: Validate the Deployment Environment

If changes to your code and configuration haven’t resolved the issue, ensure that your server environment is properly configured. This includes:

Checking the version of Tomcat and Java on the server. Ensure they match your development environment (e.g., Tomcat 9 and Java 11).

Confirming that your WAR file is correctly deployed on the server, and that your application is listening on the intended port.

Step 4: Test Application Endpoints

After applying changes, it’s crucial to verify the application. Use tools like Postman or your browser to send requests to your endpoints and ensure you receive the expected responses.

Access the application through /nameofwar, if that's your context path, to test whether the application correctly responds to requests.

Final Thoughts

Facing a 404 Error after deploying your Spring Boot application can be disheartening, especially after countless hours of development. However, by systematically checking your controller annotations, application properties, deployment environment, and endpoint accessibility, you can effectively resolve these issues.

For further troubleshooting, always refer to the logs for any runtime errors that may give additional insight into underlying problems. With patience and methodical debugging, you will have your application up and running on the s

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