How to Migrate Your Application to Spring Boot 2.0: Essential Steps and Tips

Prerequisites

Spring Boot 2.0 requires Java 8 or higher. Many configuration properties have been renamed or removed, so application.properties or application.yml files must be updated.

Properties Migrator

Add the spring-boot-properties-migrator module to your project to analyze the environment and print diagnostic information at startup. After migration, remove this dependency.

<ol>
<li><code><dependency></code></li>
<li><code><groupId>org.springframework.boot</groupId></code></li>
<li><code><artifactId>spring-boot-properties-migrator</artifactId></code></li>
<li><code></dependency></code></li>
</ol>

Building Your Spring Boot Application

Maven Plugin

All exposed plugin configuration properties now start with the spring-boot prefix. Example to run with a profile:

mvn spring-boot:run -Dspring-boot.run.profiles=prod

Gradle Plugin

The Spring Boot Gradle plugin has been rewritten. Apply the plugin and the dependency‑management plugin explicitly:

<ol>
<li><code>apply plugin: 'org.springframework.boot'</code></li>
<li><code>apply plugin: 'io.spring.dependency-management' // add this to your build.gradle</code></li>
</ol>

Key Spring Boot 2.0 Changes

Default Dynamic Proxy Strategy

CGLIB is now the default for class‑based proxies. To use interface‑based proxies, set spring.aop.proxy-target-class=false.

Web Application Type

The deprecated spring.main.web-environment property is replaced by spring.main.web-application-type. To disable the web server, set it to none or call SpringApplication.setWebApplicationType(...).

Application Events

A new ApplicationStartedEvent is published after the context is refreshed but before command‑line runners execute. ApplicationReadyEvent now signals that the application is ready to serve requests.

Banner Configuration

Banner‑related properties have been moved to the spring.banner namespace.

Relaxed Binding

Relaxed binding now supports kebab‑case, camelCase, and snake_case for property names, and environment variables must use upper‑case with underscores. The old RelaxedPropertyResolver and RelaxedDataBinder classes have been removed in favor of the new Binder API.

Embedded Servlet Container Refactoring

EmbeddedServletContainer

has been renamed to WebServer. Packages have moved from org.springframework.boot.context.embedded to org.springframework.boot.web.embedded. For example, replace TomcatEmbeddedServletContainerFactory with TomcatServletWebServerFactory.

Servlet‑Specific Server Properties

All server.* servlet properties have been moved under server.servlet.*. Example mappings: server.context-path →

server.servlet.context-path

server.jsp.class-name

→

server.servlet.jsp.class-name

server.servlet-path

→

server.servlet.path

Web Starter Dependencies

Spring Boot 2.0 no longer pulls in WebFlux‑related starters automatically. Choose the appropriate starter ( spring-boot-starter-web or spring-boot-starter-webflux) yourself.

Template Engine Extensions

Mustache templates now use the .mustache suffix by default; adjust spring.mustache.suffix if needed.

Jackson / JSON

Jackson now writes dates as ISO‑8601 strings. To revert to timestamps, set spring.jackson.serialization.write-dates-as-timestamps=true. The spring-boot-starter-json starter bundles the necessary Jackson modules.

Spring MVC Path Matching

Suffix‑based path matching is disabled by default. Set spring.mvc.pathmatch.use-suffix-pattern to true if the old behavior is required.

Servlet Filter Dispatcher Type

Filters now default to DispatcherType.REQUEST, matching the Servlet specification.

RestTemplateBuilder

The requestFactory method now accepts a Supplier<ClientHttpRequestFactory>, allowing each template to use its own factory.

WebJars Locator

The old webjars-locator core library has been renamed; update dependencies accordingly.

Security Simplification

Adding a custom WebSecurityConfigurerAdapter disables most auto‑configuration. Security properties have moved under the security namespace. The default user now has a generated password and can be customized via spring.security.user.*.

Actuator Overhaul

Actuator endpoints are now under /actuator by default. Configuration keys have moved from endpoints.* to management.endpoint.* and management.endpoints.web.*. The base path can be changed with management.endpoints.web.base-path. Endpoint exposure is controlled via management.endpoints.web.exposure.include and management.endpoints.web.exposure.exclude. The health endpoint now uses management.endpoint.health.show-details to control detail visibility.

Metrics Migration

Spring Boot’s native metrics have been replaced by Micrometer. Use MeterRegistry or static Metrics.counter(...) calls to create custom metrics.

Developer Tools

Spring Loaded support has been removed; use Spring Boot DevTools instead. Remote HTTP tunnel debugging has also been dropped.

Removed Features

CRaSH support, Spring Mobile, Spring Social auto‑configuration, and the commons-digester dependency management have been removed.

Dependency Versions

Spring Boot 2.0 requires newer versions of key libraries: Spring Framework 5, Spring Security 5, Hibernate 5.2, Elasticsearch 5.6+, Jetty 9.4, Tomcat 8.5, and Gradle 4.

Reference

For the full migration guide, see the official repository: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide