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Spring Boot 4.2.0 RC1 Release Notes

Moritz Halbritter edited this page Sep 24, 2026 · 4 revisions

Spring Boot 4.2.0-RC1 Release Notes

For changes in earlier milestones, please refer to:

Upgrading from Spring Boot 4.1

New and Noteworthy

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

Default Buildpacks Builder Changed to Ubuntu Resolute

The default builder used by the Maven and Gradle plugins to build OCI images is now paketobuildpacks/ubuntu-resolute-builder, replacing paketobuildpacks/builder-noble-java-tiny. Images are now based on Ubuntu 26.04 instead of 24.04.

When builder is not configured, the run image defaults to paketobuildpacks/ubuntu-resolute-run-tiny:latest, which, like before, does not include a shell. When builder is configured, the run image from the builder metadata is used, which is paketobuildpacks/ubuntu-resolute-run:latest and includes a shell.

The run image is no longer pinned to a specific version by the builder. If you need reproducible images, set both builder and runImage to specific versions.

To keep using the previous builder, set builder to paketobuildpacks/builder-noble-java-tiny.

Run Image Compatibility Check Uses OS Distribution

The Maven and Gradle plugins no longer compare the deprecated stack IDs of the builder and run image. Instead, they compare the OS distribution taken from the io.buildpacks.base.distro. labels, falling back to the io.buildpacks.stack.distro. labels. A warning is logged if the name or version differs, for example when using a paketobuildpacks/ubuntu-noble-run run image with the default resolute builder.

Dependency Upgrades

Spring Boot 4.2.0-RC1 moves to new versions of several Spring projects:

  • TBD

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

  • TBD

Miscellaneous

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

  • TBD

Deprecations in Spring Boot 4.2.0-RC1

  • TBD

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