# Upgrading Spring Boot — Spring Boot

Source: https://www.skillbyai.com/en/spring-boot/p-upgrade

> Stay on supported versions.

## Release notes, migration guides, OpenRewrite

Spring Boot releases frequently and supports each version for a limited time, so plan regular upgrades. Read the release notes and migration guide for each step (Spring Boot 4 brought modular starters such as spring-boot-starter-webmvc, new test-module packages for slice annotations, and a Java 17 baseline). Upgrade one minor version at a time, run the full test suite, and consider automated refactoring with OpenRewrite recipes. Keep dependencies managed by Boot's BOM.

## Boot 4 changes seen in this course

Observed while building the demo; check the official migration guide for the full list.

```text
web starter          spring-boot-starter-webmvc (servlet stack)
test starters        per technology, e.g. spring-boot-starter-webmvc-test
@WebMvcTest package  org.springframework.boot.webmvc.test.autoconfigure
@DataJpaTest package org.springframework.boot.data.jpa.test.autoconfigure
mocking              @MockitoBean (org.springframework.test.context.bean.override.mockito)
baseline             Java 17+ (this course used Java 21)
```

## Upgrade often in small steps

Small, regular upgrades are far cheaper than jumping several major versions at once.

**Quiz:** What is a safe way to upgrade Spring Boot?

- [ ] Override every managed dependency version
- [ ] Skip several major versions without testing
- [x] One version at a time, following the migration guide and running all tests
- [ ] Never upgrade

*Answer:* One version at a time, following the migration guide and running all tests. Incremental, tested upgrades.