Release thread for Scala 3.1.3

I was advised that making a single thread for the entire release process of a new scala version would be easier to follow and less chaotic than putting up a new thread every time we publish a release candidate.

So here we are. The release thread for 3.1.3. Posts about the previous RCs can be found here:


In the meantime, we have started running our new Unmanaged Community Build. It allowed us to find obscure regressions in the recent releases of the compiler. We have managed to fix some of them and we are shipping them now in 3.1.3-RC4.

This postpones the release of stable 3.1.3 for another week. Right now the predicted date of the release is June 1st.


We still have a long list of regressions found by Unmanaged Community Build. Knowing that 3.1.3 is the last release in the 3.1 line, we are committed to fixing most of them in this release. This however pushes the release further back. Expect at least one release candidate more and the stable version in no less than two weeks.


Can you elaborate or provide a link on “Knowing that 3.1.3 is the last release in the 3.1 line, …”?

Is there a missing “before the release of 3.2.0”? Or is it implying a hard stop for the 3.1.x line?

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3.2.0 is the next version that is being developed right now. That means there will be no 3.1.4. It is not a big deal as we keep backward compatibility between minor releases (in this case, between 3.1 and 3.2). That means you can use libraries compiled with 3.1 (or even 3.0) as your dependencies in the 3.2 project. Regarding source compatibility, updating from 3.1 to 3.2 will be as easy as updating from 3.1.1 to 3.1.2.

We are no longer in Scala 2 world, where 2.12 and 2.13 were different compilation targets and needed cross-compilation.

There is still, of course, the problem of forward compatibility, which may be important for projects that are unable to update for some specific reasons. We plan to address that by the LTS version (currently scheduled for 3.3). The blog post announcing this is now under public review.


3.1.3-RC5 is available for testing. The team managed to fix all significant regressions. The full release should be public in around one week.


I’ve started the release procedure for 3.1.3. The artifacts are published and should soon be visible on Maven Central.

You can follow the procedure here: 3.1.3 & 3.2.0-RC1 Release procedure · Issue #15436 · lampepfl/dotty · GitHub.

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… aaand it is out!



Metals should also support the most recent version already. Let us know if there are any issue.


Scala Native down to version 0.4.3 also supports Scala 3.1.3!