Scala 2.12.17 release planning

This thread is for updates and discussions about the upcoming Scala 2.12.17 release.

Scala 2.12.16 (released June 10) included one regression. A fix has already been merged, and we said we’d release that fix in no less than “2–3 months”.

If you’re aware of anything else you think ought to be considered a blocker for this release, please let us know, either by commenting on the appropriate ticket or PR, or by replying on this thread.

At present there are no known blockers and no open issues or PRs on the 2.12.17 milestones in scala/bug and scala/scala.

The most significant changes already merged are listed here:


If you’re aware of anything else you think ought to be considered a blocker for this release

If gets merged for 2.13.9, it would be nice to have it backported in time for 2.12.17 too, for consistency and ease of cross-compilation.


For 2.12.17, we may upgrade scala-compiler’s dependency on scala-xml 1.x to 2.x. Please join the discussion at if you want to say something for or against this proposed change.

1 Like

We currently plan to build 2.12.17 and 2.13.9 in tandem, once Scala 3.2.0 final is out — hopefully next week!


We believe we have now merged the last 2.12.17 PR. The milestones are closed. The release-candidate nightly is 2.12.17-bin-45183fa, and it’s green in the community build.

Merged PRs with “release notes” label: Pull requests · scala/scala · GitHub

We’ll aim to release this as 2.12.17 on Wednesday, September 14 (perhaps later, definitely no sooner).

Draft release notes:

Feedback and suggestions on wordings welcome — you may comment on the PR.

1 Like

I checked that Scala.js v1.10.1 works with 2.12.17-bin-45183fa. :white_check_mark:


Scala Native 0.4.7 has no problems with supporting 2.12.17-bin-45183fa.

However, I’ve some problems with tests involving collecting java.lang.ref.WeakReference instances. In a single test compiled with 2.12.17 fails. The test does finish successfully using the 2.12.16 or 2.13.9 candidates. It might be an issue related to our GC implementation, and I don’t see a reason why it should lead to a delay in the release.


I checked semanticdb plugin, bloop and Metals for 2.12.17-bin-45183fa - everything is fine


Looks like the coast is clear and we can go ahead and publish 2.12.17 to Maven Central tomorrow (Wednesday), then announce it on Friday.


2.12.17 JARs are now on Maven Central.

Tooling maintainer powers, activate!

Scala.js compiler plugins from v1.7.1 to the most recent, on their way to Maven Central for Scala 2.12.17 support.


Scala Native compilers plugins from v0.4.3 to v0.4.7 (the most recent) are on their way to Maven Central


Scalameta semanticdb plugin has been back published for versions 4.5.11, 4.5.12 and 4.5.13. :tada:

Metals 0.11.8 already supports Scala 2.12.17 and all the next snapshots will support it also.


scalafix & sbt-scalafix 0.10.2 are out with support for Scala 2.12.17


Announcements made!

1 Like