How do you configure error pages in Spring Boot applications?

Table of Contents

• Introduction
  • Configuring Error Pages in Spring Boot
    • 1. Using the **application.properties** or **application.yml** File
      • Example: Configure Custom Error Pages in application.properties
      • Example: Custom Error Page for 404
    • 2. Using the **ErrorController** Interface
      • Example: Implementing ErrorController for Custom Error Pages
      • Example: Custom Error Page (Thymeleaf Template)
    • 3. Handling Specific HTTP Status Codes
      • Example: Handling HTTP 404 Error
      • Example: Handling HTTP 500 Error
    • 4. Using **@ControllerAdvice** for Global Error Handling
      • Example: Handling Global Exceptions with @ControllerAdvice
    • 5. Custom Error Pages for Specific Exception Types
      • Example: Handling NullPointerException
  • Best Practices for Error Handling in Spring Boot
• Conclusion

Introduction

Handling errors gracefully is an essential part of any web application. In Spring Boot, configuring error pages can enhance the user experience by providing friendly, informative messages instead of generic error responses. Whether it's a "404 Not Found" or a custom exception, Spring Boot offers multiple ways to handle errors and configure custom error pages.

This guide will explain how to configure custom error pages in Spring Boot applications, covering built-in error page handling, the ErrorController interface, and how to customize error templates.

Configuring Error Pages in Spring Boot

There are several ways to configure error pages in Spring Boot, depending on the type of error (HTTP error codes like 404, 500, etc., or application exceptions).

1. Using the **application.properties** or **application.yml** File

Spring Boot automatically provides a default error page for common HTTP errors, but you can configure custom error pages for specific HTTP status codes using the application.properties or application.yml file.

Example: Configure Custom Error Pages in application.properties

• server.error.whitelabel.enabled=false disables Spring Boot's default "whitelabel" error page and allows you to define your own error pages.
• server.error.path=/error allows you to customize the path to the error page. By default, it's /error.

To create a custom error page, you can then create an HTML or Thymeleaf template file under the resources directory.

Example: Custom Error Page for 404

This page will be displayed when a 404 error occurs.

2. Using the **ErrorController** Interface

For more fine-grained control over error handling, Spring Boot provides the ErrorController interface, which allows you to define custom error handling logic.

Example: Implementing ErrorController for Custom Error Pages

• The handleError() method handles the /error URL and returns a custom error view.
• You can create a custom error page, for example, customError.html, in the resources/templates folder.

Example: Custom Error Page (Thymeleaf Template)

• When an error occurs, Spring Boot will call the /error endpoint, which will return the customError view.

3. Handling Specific HTTP Status Codes

You can handle specific HTTP errors, like 404 (Not Found) or 500 (Internal Server Error), with dedicated mappings. You can use the @RequestMapping annotation to map specific HTTP status codes.

Example: Handling HTTP 404 Error

• Create an HTML page named error404.html in the resources/templates folder.

Example: Handling HTTP 500 Error

• Create a page named error500.html in resources/templates.

4. Using **@ControllerAdvice** for Global Error Handling

@ControllerAdvice allows you to handle errors globally across all controllers. You can use it to catch specific exceptions and show a custom error page.

Example: Handling Global Exceptions with @ControllerAdvice

• This @ControllerAdvice will catch all exceptions globally, display the error message, and render a custom error page named globalError.html.

5. Custom Error Pages for Specific Exception Types

You can also configure custom error pages for specific exception types (like NotFoundException or DatabaseException) using @ExceptionHandler.

Example: Handling NullPointerException

• When a NullPointerException is thrown, Spring will render the nullPointerError.html page.

Best Practices for Error Handling in Spring Boot

1. Provide Clear, User-Friendly Error Pages: Always aim to give users helpful error messages when something goes wrong. Avoid showing raw stack traces or technical details.
2. Handle Common Errors (404, 500): Customize pages for common HTTP errors like 404 (Not Found) and 500 (Internal Server Error) to improve user experience.
3. Use **ErrorController** for Flexibility: Use ErrorController for more control over error handling and to centralize error logic.
4. Handle Specific Exceptions: Use @ControllerAdvice to globally handle specific exceptions and customize error responses for different scenarios.
5. Ensure Graceful Redirection: When users encounter errors, provide clear next steps, such as offering links to the homepage or support.

Conclusion

Configuring custom error pages in Spring Boot is a powerful way to improve the user experience by providing clear feedback when something goes wrong. Spring Boot offers multiple approaches for handling errors, from simple configurations in application.properties to more advanced solutions using ErrorController and @ControllerAdvice. By customizing error pages for HTTP status codes or exceptions, you can ensure your application handles errors gracefully and provides users with helpful, actionable information.