sbt 1.5.2


I'm happy to announce sbt 1.5.2 patch release is available. Full release note is here -

Bintray to JFrog Artifactory migration status and sbt 1.5.1


I'm happy to announce sbt 1.5.1 patch release is available. Full release note is here - This post will also report the Bintray to JFrog Artifactory migration.

There's now a cloud-hosted Artifactory instance licensed to Scala Center. Let's call this "Artsy" in this post instead of the Artifactory instance. With the release of sbt 1.5.1, I think we can say that the migration is done.

herding cats: day 19


Wrote herding cats: day 19 featuring FunctionK, or Rúnar's encoding of rank-2 polymorphic function, and Resource datatype, which he envisioned rank-N polymorphism would unlock back in 2010.

sbt 1.5.0


Hi everyone. On behalf of the sbt project, I am happy to announce sbt 1.5.0. This is the fifth feature release of sbt 1.x, a binary compatible release focusing on new features. sbt 1.x is released under Semantic Versioning, and the plugins are expected to work throughout the 1.x series.

The headline features of sbt 1.5.0 are:

  • Scala 3 support
  • Eviction error
  • Deprecation of sbt 0.13 syntax
  • Coursier-based launcher

How to upgrade

sbt 1.4.9


I'm happy to announce sbt 1.4.9 patch release is available. Full release note is here -


  • sbt 1.4.9 fixes JLine 2 fork + JAnsi version to match that of JLine 3.19.0 to fix line reading, which among other things affected IntelliJ import.
  • sbt 1.4.9 is a maintenance patch. The most notable thing is that this was that it was released without using Bintray, and a few things were dropped. See below for details.

sbt 1.4.9 is published to Sonatype OSS without going through Bintray.

  • Prior to 1.4.8, sbt-launcher was published twice under sbt-launch.jar and Maven-compatible sbt-launch-<version>.jar. We're no longer going to publish the Maven incompatible form of the launcher JAR. The latest sbt-extras has already migrated to the correct URL, but CI environments using an older version of it may experience disruptions.
  • DEB and RPM packages are not provided for this release. I hope we will have a replacement repo up to eventually be able to support this, but we do not have one yet. For now, download *.tgz from GitHub release.

syntactic Scalafix rule for unified slash syntax


I was able to hack together a syntactic Scalafix rule to convert build.sbt to unified slash syntax.


Make sure your project is on git or make a backup.

$ cs install scalafix
$ export PATH="$PATH:$HOME/Library/Application Support/Coursier/bin"
$ scalafix --rules= *.sbt project/*.scala

It might not be precise, but it surely beats doing it by hand.

git bisecting scala/scala


git bisecting is a useful technique to locate the source of a bug. For scala/scala in particular, can save a lot of time by using the pre-build compiler artifacts on the Scala CI Artifactory.

sbt 1.4.7


I'm happy to announce sbt 1.4.7 patch release is available. Full release note is here -

How to upgrade

Download the official sbt launcher from SDKMAN or download from

In addition, the sbt version used for your build is upgraded by putting the following in project/


This mechanism allows that sbt 1.4.7 is used only for the builds that you want.


enforcing Semantic Versioning with sbt-strict-update

ThisBuild / scalaVersion := "2.13.3"
ThisBuild / libraryDependencySchemes += "org.typelevel" %% "cats-effect" % "early-semver"
lazy val root = (project in file("."))
    name := "demo",
    libraryDependencies ++= List(
      "org.http4s" %% "http4s-blaze-server" % "0.21.11",
      "org.typelevel" %% "cats-effect" % "3.0-8096649",

Now if Rob tries to compile this build, he should get:

sbt:demo> compile
[warn] There may be incompatibilities among your library dependencies; run 'evicted' to see detailed eviction warnings.
[error] stack trace is suppressed; run last update for the full output
[error] (update) found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
[error]   * org.typelevel:cats-effect_2.13:3.0-8096649 (early-semver) is selected over {2.2.0, 2.0.0, 2.0.0, 2.2.0}
[error]       +- demo:demo_2.13:0.1.0-SNAPSHOT                      (depends on 3.0-8096649)
[error]       +- org.http4s:http4s-core_2.13:0.21.11                (depends on 2.2.0)
[error]       +- io.chrisdavenport:vault_2.13:2.0.0                 (depends on 2.0.0)
[error]       +- io.chrisdavenport:unique_2.13:2.0.0                (depends on 2.0.0)
[error]       +- co.fs2:fs2-core_2.13:2.4.5                         (depends on 2.2.0)
[error] Total time: 0 s, completed Dec 13, 2020 11:53:31 PM
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