Kotlin Multiplatform Dec 16, 2025

v2.3.0

What's New

Kotlin 2.3.0 stabilizes K2 as the default compiler with significant improvements to debugging, Analysis API capabilities, and Wasm support. The release includes 50+ bug fixes across debugger, type inference, and incremental compilation, plus performance optimizations in caching and Native backend. K1 decompiler is removed and replaced with a K2 implementation offering better stub consistency.

Highlights

Breaking Changes

  • Language versions 1.8 and 1.9 dropped for non-JVM platforms
  • K1 decompiler removed in favor of K2 implementation
  • KaImportOptimizer API dropped from Analysis API

Deprecations

  • Local type aliases restricted to REPL/scripts pending full stabilization
  • Kotlin/Native eager GlobalData initialization deprecated
  • Package-private parameter exposure in internal methods now deprecated with warning

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