Last mile towards sbt 2

Eugene Yokota

This post covers work done under the Sovereign Tech Fund investment umbrella: sbt 2 Stable Release and Maintenance. The work is coordinated by the Scala Center.

At conferences or on social media, the question we get most often is:

When is sbt 2 coming out?

We’ll discuss the plan in this post. But let’s go over the status first.

What’s new in sbt 2?

sbt 2 is a new major version of sbt. If you’re familiar with sbt 1.x, hopefully the jump is not too far, but we have pushed sbt to a more modern standard. The headline features are:

  • sbt 2.x uses Scala 3.x (rather than Scala 2.12) for build definitions and plugins (Both sbt 1.x and 2.x are capable of building Scala 2.x and 3.x)
  • Embraces a simpler build.sbt via common settings
  • test changed to an incremental test
  • Local and remote cache system that is Bazel-compatible
  • Uses sbtn (native-image client) for faster startup
  • Project matrix that can cross build subprojects in parallel


For more details, please check out the Scala Days 2025 talk sbt 2.0: go big that I gave in August 2025.

To share the progress thus far, we released the sbt 2.0 ideas post in 2023, with sbt 2.0.0-alpha7. After a few more years of development, we released a beta version sbt 2.0.0-RC2 that’s ready for testing, around Scala Days 2025. Since then, we have been releasing more beta versions with both bug fixes and community-contributed feature enhancements. Perhaps surprising to some, sbt 2.x already started the binary compatibility from the RC series. This gave us a head start on repopulating the plugin ecosystem.

Repopulating the plugin ecosystem

Thanks to the community effort, we already have 60+ plugins ported to sbt 2.x. This is amazing for a build tool that hasn’t been released yet. Special thanks to Kenji Yoshida for pull requests, preparing and porting many plugins to sbt 2.

Under the sbt 2 workstream, Anatolii from Scala Center has created the sbt2-compat plugin, which bridges the source-level differences between sbt 1.x and 2.x. This allows cross-building of a plugin, aiding the migration process. Also under the STA workstream, Rikito Taniguchi from VirtusLab has created a pull request to cross build Scala.JS plugin to sbt 2.x (scala-js#5314).

Plugin Version Published Notes
Scala Native 0.5.11 ✅  
sbt-assembly 2.3.1 ✅  
Play 3.1.0-M9 ⚠️ Pending scripted tests.
Scala.JS n/a n/a Pending scala-js#5314

Independently, the Play and Scala Native projects have been working towards sbt 2.x support as well.

Tooling support and documentation

Both IntelliJ Scala Plugin and Metals have published sbt plugins to import sbt 2.x projects.

Documentation has been reorganized and partly rewritten as The book of sbt, which has also been translated to Japanese and Chinese.

Locking down to 2.0.x branch

We have now created the 2.0.x branch, so by default, all pull requests will target sbt 2.1. Only the critical bug fixes will be backported to the 2.0.x branch.

Next steps: Please try using the latest RC on your projects, and check out the newly updated documentation. If you find bugs or missing documentation, please let us know by creating an issue on GitHub.

We will likely release a few more release candidates, but if no critical bugs are found, we will graduate one of them to the final release. So when is sbt 2 coming out? Depending on the bugs we discover, we are hopeful that it can happen in a few weeks to a few months.

Participation

The Scala Center has been entrusted with coordinating the commissioned Scala work for the Sovereign Tech Fund. The Scala Center is an independent, not-for-profit center sponsored by corporate members and individual backers like you to promote and facilitate Scala. If you would like to participate and/or see more of these types of efforts, please reach out to your manager to see if your company can donate engineering time or membership to the Scala Center.

See The Scala Center Fundraising Campaign for more details.

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