The Mysterious Case of Spring and Swagger: Deciphering the /swagger-resources/configuration/ui 404 NOT FOUND Error

Are you a Spring developer who’s recently ventured into the realm of Swagger, only to be greeted by the ominous 404 NOT FOUND error when attempting to access the /swagger-resources/configuration/ui endpoint? Fear not, dear reader, for you are not alone in this struggle. In this article, we’ll delve into the world of Spring and Swagger, exploring the reasons behind this perplexing issue and providing a step-by-step guide to resolve it once and for all.

The Spring-Swagger Conundrum

Before we dive into the solution, let’s set the stage by understanding the basics of Spring and Swagger.

Spring is a popular Java-based framework for building robust and scalable web applications. It provides a comprehensive set of tools and libraries to streamline the development process, making it a favorite among developers.

Swagger, on the other hand, is an open-source tool that helps generate beautiful, interactive API documentation. It allows developers to visualize and test their APIs in a user-friendly interface, making it an essential tool for API development.

When used together, Spring and Swagger form a powerful duo, enabling developers to create well-documented and easily consumable APIs. However, as you’ve probably discovered, this union is not without its challenges.

The Enigmatic /swagger-resources/configuration/ui 404 NOT FOUND Error

The error in question is a common stumbling block for many developers. You’ve set up your Spring project, configured Swagger, and yet, when you attempt to access the /swagger-resources/configuration/ui endpoint, you’re met with a 404 NOT FOUND error. It’s as if the endpoint has vanished into thin air.

But fear not, dear reader, for we’re about to uncover the reasons behind this enigmatic error and provide a solution that will have you up and running in no time.

Reasons Behind the /swagger-resources/configuration/ui 404 NOT FOUND Error

Before we dive into the solution, let’s explore the possible reasons behind this error.

• Swagger Configuration Issues: Misconfigured Swagger settings can lead to the 404 NOT FOUND error. This might include incorrect annotation, missing dependencies, or incorrect API path definitions.
• Spring Boot Version Incompatibility: Incompatibility between Spring Boot versions and Swagger can cause this error. Ensure that you’re using compatible versions of both.
• Lack of Swagger UI Dependency: Failing to include the Swagger UI dependency in your project can prevent the /swagger-resources/configuration/ui endpoint from functioning correctly.
• Misconfigured Spring Security: Overly restrictive Spring Security settings can block access to the /swagger-resources/configuration/ui endpoint, resulting in the 404 NOT FOUND error.

Step-by-Step Solution to the /swagger-resources/configuration/ui 404 NOT FOUND Error

Now that we’ve explored the possible reasons behind the error, let’s provide a comprehensive solution to resolve it once and for all.

Step 1: Verify Swagger Configuration

First, ensure that your Swagger configuration is correct. Check that you’ve included the necessary annotations, dependencies, and API path definitions.

@SpringBootApplication
@EnableSwagger2
public class MyApplication {
  
  @Bean
  public Docket api() {
    return new Docket(DocumentationType.SWAGGER_2)
      .select()
      .apis(RequestHandlerSelectors.any())
      .paths(PathSelectors.any())
      .build();
  }
}

Step 2: Verify Spring Boot Version Compatibility

Next, ensure that you’re using compatible versions of Spring Boot and Swagger. You can check the Spring Boot version by looking at your project’s pom.xml file (if you’re using Maven) or build.gradle file (if you’re using Gradle).

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.3.4.RELEASE</version>
  </dependency>
  <dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-boot-starter</artifactId>
    <version>3.0.0</version>
  </dependency>
</dependencies>

Step 3: Add Swagger UI Dependency

Include the Swagger UI dependency in your project to enable the /swagger-resources/configuration/ui endpoint.

<dependencies>
  <dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>3.0.0</version>
  </dependency>
</dependencies>

Step 4: Configure Spring Security (Optional)

If you’re using Spring Security, ensure that you’re not blocking access to the /swagger-resources/configuration/ui endpoint.

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
  
  @Override
  protected void configure(HttpSecurity http) throws Exception {
    http.authorizeRequests()
      .antMatchers("/swagger-ui/**", "/swagger-resources/**", "/swagger-ui.html")
      .permitAll();
  }
}

Conclusion

In conclusion, the /swagger-resources/configuration/ui 404 NOT FOUND error is a common issue that can be resolved by following these simple steps. By verifying your Swagger configuration, ensuring Spring Boot version compatibility, adding the Swagger UI dependency, and configuring Spring Security (if necessary), you’ll be able to access the /swagger-resources/configuration/ui endpoint and enjoy the benefits of Swagger’s interactive API documentation.

Remember, dear reader, that patience and persistence are key when troubleshooting errors. Take your time, follow these steps, and you’ll be well on your way to resolving the mysterious case of the /swagger-resources/configuration/ui 404 NOT FOUND error.

Spring Version	Swagger Version
Spring Boot 2.3.4.RELEASE	Swagger 3.0.0
Spring Boot 2.2.6.RELEASE	Swagger 2.9.2

For a comprehensive list of compatible Spring Boot and Swagger versions, consult the official documentation for both frameworks.

1. Spring Boot Official Documentation
2. Swagger Official Documentation

Happy coding, and may the Swagger force be with you!

Frequently Asked Question

Spring and Swagger, a match made in heaven, right? Well, until you stumble upon the dreaded “/swagger-resources/configuration/ui 404 NOT FOUND” error, that is. Don’t worry, we’ve got you covered! Here are some frequently asked questions to help you troubleshoot and resolve this pesky issue.