Only relevant change: "Web and WebFlux starters do not depend on the validation starter by default anymore. If your application is using validation features, for example you find that javax.validation.* imports are not being resolved, you’ll need to add the starter yourself."
Upgrade guide: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.3-Release-Notes#upgrading-from-spring-boot-22
Only relevant change: "Web and WebFlux starters do not depend on the validation starter by default anymore. If your application is using validation features, for example you find that javax.validation.* imports are not being resolved, you’ll need to add the starter yourself."