How to Fix Spring Boot 3 and Swagger 2 Compatibility Issues

Spring Boot 3 and Swagger 2 are not compatible because Swagger 2 relies on the javax packages while Spring Boot 3 uses the jakarta packages. The usual workaround is to downgrade to Spring Boot 2.x or switch to a Jakarta‑compatible documentation tool such as Springdoc.

To keep using Swagger 2 with Spring Boot 3, first check the Spring framework version in pom.xml . If you are on the latest 3.3.1, change the Spring Boot version to 2.7.2 and refresh the project.

After the downgrade, classes that import HttpServletRequest and HttpServletResponse will still error because they reference javax.servlet . Replace those imports with the Jakarta equivalents and add the following Maven dependency:

<code><dependency>
  <groupId>jakarta.servlet</groupId>
  <artifactId>jakarta.servlet-api</artifactId>
  <version>6.0.0</version>
  <scope>provided</scope>
</dependency></code>

Import statements should be changed to:

<code>import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;</code>

If you encounter runtime failures, verify that your Java version is supported (Java 21 may cause issues). Also add the following property to application.properties to avoid a conflict between Spring Boot 2.6+ and Swagger:

<code>spring.mvc.pathmatch.matching-strategy=ant_path_matcher</code>

Next, add the Swagger 2 dependencies to pom.xml :

<code><dependency>
  <groupId>io.springfox</groupId>
  <artifactId>springfox-swagger2</artifactId>
  <version>2.9.2</version>
</dependency>
<dependency>
  <groupId>io.springfox</groupId>
  <artifactId>springfox-swagger-ui</artifactId>
  <version>2.9.2</version>
</dependency></code>

Create a configuration class in the config package:

<code>@Configuration
@EnableSwagger2
public class SwaggerConfig {
    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .select()
                .apis(RequestHandlerSelectors.basePackage("com"))
                .paths(PathSelectors.any())
                .build();
    }

    /**
     * API documentation meta‑information
     */
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("Demo Project API")
                .description("Learning Swagger2 with a demo project")
                .version("1.0")
                .build();
    }
}
</code>

After rebuilding, the application starts successfully and the Swagger UI can be accessed at http://localhost:8080/swagger-ui.html .