Kotlin Multiplatform Oct 28, 2025 Pre-release

v2.3.0-Beta2

What's New

Kotlin 2.3.0-Beta2 delivers significant K2 compiler stability with 40+ critical bug fixes for type inference, generics, and Java interop. Major platform improvements include WebAssembly module-per-klib support, Swift Export async function integration, and Kotlin/JS default export capability. The release emphasizes tooling modernization with Gradle 9.0 support, Build Tools API refinements, and stdlib enhancements like UUID v7 generation, while consolidating deprecated APIs across Gradle plugins and multiplatform development.

Highlights

Breaking Changes

  • Promoted multiple Gradle JS/Wasm deprecations to ERROR: ExperimentalWasmDsl, ExperimentalDceDsl, phantom-js, internal functions
  • Deprecated androidTarget in Kotlin Multiplatform Plugin
  • Deprecated org.jetbrains.kotlin.android plugin
  • kotlin.io.createTempDir and createTempFile deprecation level increased to ERROR
  • String.subSequence(start, end) deprecated with error level
  • Removed language version 1.9 support for non-JVM platforms
  • Removed bitcode DSL from Native Gradle configuration

Deprecations

  • Old BTA prototype API deprecated in favor of new Build Tools API
  • HasKotlinDependencies usage inside KotlinCompilation deprecated
  • NPM and Yarn package manager internal functions deprecated
  • Symbols deprecated after KT-54312 removed from Gradle plugin

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