Spring Boot 4.0.0 RC1 Release Notes

Spring Boot 4.0.0-RC1 Release Notes

For changes in earlier milestones, please refer to:

• v4.0.0-M3

• v4.0.0-M2

• v4.0.0-M1

Upgrading from Spring Boot 3.5

Migration Guide

To help with upgrading, a migration guide is available.

Classic Uber-Jar Loader Support

The classic uber-jar loader has been removed from this release. You should remove any loader implementation configuration from your build file.

For maven this means removing the following:

<loaderImplementation>CLASSIC</loaderImplementation>

For Gradle, it will be lines similar to:

loaderImplementation = org.springframework.boot.loader.tools.LoaderImplementation.CLASSIC

Optional Dependencies in Maven

Optional dependencies are no longer included in uber jars. If you need them, you can use the configuration setting <includeOptional>true</includeOptional>

Jackson

The JSON-specific spring.jackson.read.* and spring.jackson.write.* properties have moved beneath spring.jackson.json.read and spring.jackson.json.write respectively.

Minimum Requirements Changes

None.

New and Noteworthy

Tip	Check the configuration changelog for a complete overview of the changes in configuration.

Dependency Upgrades

Spring Boot 4.0.0-RC1 moves to new versions of several Spring projects:

• TODO

Numerous third-party dependencies have also been updated, some of the more noteworthy of which are the following:

• TODO

Miscellaneous

Apart from the changes listed above, there have also been lots of minor tweaks and improvements including:

• You can now set Spring-Boot-Jar-Type to development-tool in your MANIFEST.MF to exclude dependencies from uber jars.

Deprecations in Spring Boot 4.0.0-RC1

• None