Troubleshooting 404 Not Found Errors in Spring Boot with Postman

A comprehensive guide to fixing `404 Not Found` errors in Spring Boot when using Postman for GET requests. Learn how to structure your requests correctly!
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Troubleshooting 404 Not Found Errors in Spring Boot with Postman

As a newcomer to Postman and Spring Boot development, it can be frustrating to encounter errors while trying to access your endpoints. One of the most common issues you may face is a 404 Not Found error when making simple GET requests. In this guide, we will guide you through the steps to resolve this issue and successfully access your API endpoints.

Understanding the Problem

When you attempt to send a GET request to your Spring Boot application using Postman and receive a 404 Not Found error, it can be due to several reasons. Let’s take a closer look at the error response you may have encountered:

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This response indicates that the requested URL could not be found, which typically signifies an issue with the request URL or the configuration within your Spring Boot application.

Solution Steps

Here are the steps to troubleshoot and fix the issue, ensuring that your GET request works as expected.

1. Verify the Request URL

Firstly, double-check the URL you are using in Postman. Based on the provided controller code, the correct endpoint for accessing the getCountries() method should be structured as follows:

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2. Update Your Spring Controller

Ensure that the @ GetMapping annotation in your controller class is correctly set up to match the URL you want to reach. The code snippet for your controller could be updated like this:

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Having both @ RequestMapping and @ GetMapping correctly configured with leading slashes is crucial for routing.

3. Confirm the Server Port Configuration

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4. Testing the Endpoint

Once these adjustments are made, restart your Spring Boot application. You can now try sending your GET request again through Postman to the updated URL:

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5. Security Considerations

If you had previously encountered a 401 Unauthorized error due to Spring Security being enabled, ensure that you properly configure or disable Spring Security while you are in development mode. This can prevent further access issues.

Conclusion

By following the steps outlined above, you should now be equipped to resolve 404 Not Found errors while working with Spring Boot and Postman. Always ensure that your URLs are correctly formed, your controller methods are properly annotated, and that your application configuration corresponds with your setup expectations.

If you continue to experience issues, revisit your configurations, and double-check your request URLs. Happy coding!