Spring Boot 3.0 Migration Skill

Common Migration Patterns

Jakarta EE Import Migration

// javax.servlet → jakarta.servlet
import jakarta.servlet.Servlet;

// javax.persistence → jakarta.persistence
import jakarta.persistence.Entity;

// javax.mail → jakarta.mail
import jakarta.mail.Session;

Auto-Configuration Registration (v2.7 → v3.0)

# v2.7 — META-INF/spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.MyAutoConfiguration

# v3.0 — META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports
com.example.MyAutoConfiguration

@ConstructorBinding (v2.x → v3.0)

// v2.x — @ConstructorBinding at type level
@ConfigurationProperties(prefix = "app")
@ConstructorBinding
public class AppProperties { ... }

// v3.0 — remove @ConstructorBinding at type level
@ConfigurationProperties(prefix = "app")
public class AppProperties {
    // @ConstructorBinding only needed if multiple constructors
}

Spring MVC URL Matching (v2.x → v3.0)

// v2.x — /greeting matched both with and without trailing slash
@GetMapping("/greeting")

// v3.0 — /greeting/ now 404s by default
// Option 1: Add explicit path
@GetMapping("/greeting", "/greeting/")

// Option 2: Re-enable trailing slash globally
@Configuration
public class WebConfiguration implements WebMvcConfigurer {
    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        configurer.setUseTrailingSlashMatch(true);
    }
}

Actuator Endpoint (v2.x → v3.0)

# v2.x
management.endpoints.web.exposure.include=health,info,httptrace

# v3.0 — httptrace renamed to httpexchanges
management.endpoints.web.exposure.include=health,info,httpexchanges

Metrics Tag Migration (v2.x → v3.0)

// v2.x — TagContributor / TagProvider
@Component
public class CustomTagContributor implements TagContributor {
    @Override
    public Iterable<Tag> tags(String metricName, Object obj, Object obj2) { ... }
}

// v3.0 — Observation Convention
@Configuration
public class CustomObservationConfiguration {
    @Bean
    public ExtendedServerRequestObservationConvention extendedServerRequestObservationConvention() {
        return new ExtendedServerRequestObservationConvention();
    }
}

Server Header Size (v2.x → v3.0)

# v2.x — inconsistent across servers
server.max-http-header-size=8KB

# v3.0 — split into request/response
server.max-http-request-header-size=8KB

Removed Dependencies

The following have been removed in Spring Boot 3.0:

• Apache ActiveMQ
• Atomikos
• EhCache 2
• Hazelcast 3
• Apache Solr (Jetty-based client incompatible with Jetty 11)
• spring.data.cassandra.* → spring.cassandra.*
• Apache HttpClient in RestTemplate → org.apache.httpcomponents.client5:httpclient5

Dependency Coordinate Changes

Data Property Changes

# Cassandra
spring.data.cassandra.* → spring.cassandra.*

# Redis
spring.redis.* → spring.data.redis.*

Full Reference

For complete details on Flyway 9.0, Liquibase 4.17.x, Hibernate 6.1, R2DBC 1.0, Spring Batch 5.0, Spring Security 6.0, Gradle plugin changes, and Micrometer 1.10 observation model, see: → references/migration-guide.md