Kotlin Multiplatform v2.0.0-Beta2 Release Notes & Developer Guide
What's New for Developers
Kotlin 2.0.0-Beta2 delivers substantial K2 compiler stability improvements with 100+ bug fixes across type inference, smartcasts, and diagnostics. Major enhancements include improved Analysis API for IDE support, Kotlin/Wasm compilation fixes, and better multiplatform expect/actual matching. JavaScript backend gains per-file mode support and export validation, while builder inference receives stricter restrictions for safer type checking.
Highlights
- K2 compiler improvements: fixed 100+ bugs in type inference, smartcasts, and diagnostics
- Enhanced Analysis API with better IDE support for K2 and improved reference resolution
- Kotlin/Wasm compilation fixes and K1 diagnostics implementation for WebAssembly
- Multiplatform support: wider actual member visibility and improved expect/actual matching
- Builder inference restrictions and SAM conversion enhancements for better type safety
- JavaScript backend improvements including per-file mode and export type validation
Breaking Changes
- Compiler ABI change in FIR2IR may affect kotlinc plugins, requires recompilation
- Expect/actual classes now in Beta with compilation warning about potential future changes
Deprecations
- Cases where companion property is prioritized over enum entry now deprecated in K1
Recent Releases
All releases →
v2.5.0-Beta2
Oct 21, 2026
Release Notes →
v2.4.21
Oct 8, 2026
Release Notes →
v2.4.21-RC
Sep 30, 2026
Release Notes →
v2.5.0-Beta1
Sep 23, 2026
Release Notes →
v2.4.20
Sep 7, 2026
Release Notes →
v2.4.20-RC3
Sep 2, 2026
Release Notes →
v2.4.20-RC2
Aug 26, 2026
Release Notes →
v2.4.20-RC
Aug 12, 2026
Release Notes →
v2.4.20-Beta2
Jul 22, 2026
Release Notes →
v2.4.10
Jul 14, 2026
Release Notes →
v2.4.10-RC2
Jul 7, 2026
Release Notes →