Kotlin v2.4.0-RC2 released!

NewsBot · 27 May 2026 15:25

Kotlin v2.4.0-RC2 has been released.

Changelog

Backend. J2KLIB

KT-86367 [JKLIB] kotlin.Cloneable built-in class not found

Compose compiler

b/511102714 Made the default stability of non-final classes Unknown
instead of Stable

Tools. Build Tools API

KT-86395 [BTA] forward-compatibility violation: NoSuchMethodError on JvmSnapshotBasedIncrementalCompilationConfiguration. breaks IC

Tools. Gradle

KT-86346 Compiler warnings printed twice in console — once as w: and again as Gradle “Problem found:” block

Tools. Gradle. BCV

KT-86268 ABI validation tasks fail with Unsupported platform toolchain type when using kotlin.compilerVersion pointing to an older compiler after BTA migration in 2.4.0-Beta2

Tools. Gradle. Wasm

KT-86457 [Wasm, Gradle] BinaryenExec.standardOutput is silently ignored after migration to Gradle Workers

Link: Release Kotlin 2.4.0-RC2 · JetBrains/kotlin · GitHub