Kotlin Multiplatform v2.2.0-Beta2 Release Notes & Developer Guide
What's New for Developers
Kotlin 2.2.0-Beta2 delivers significant K2 compiler stability with 50+ Analysis API and FIR fixes, enhances Compose compiler with new default optimizations, and improves WebAssembly and JVM backends. The release adds Jakarta nullability support, JVM 24 bytecode targeting, and IR inliner improvements while dropping pre-1.6 language features and refining metadata handling for better tooling integration.
Highlights
- K2 compiler stability improvements with 50+ bug fixes for Analysis API and FIR
- Compose compiler enables PausableComposition and OptimizeNonSkippingGroups by default
- WebAssembly backend improvements including new RTTI approach and incremental compilation fixes
- Jakarta nullability annotations support and better value class warnings for JEP 390
- IR inliner enhancements with separate KLIB storage for preprocessed inline functions
- JVM target bytecode version 24 support and invokedynamic for lambdas without runtime annotations
Breaking Changes
- Language versions 1.6 and 1.7 dropped from compiler
- JvmDefaultWithoutCompatibility now errors when used with -Xjvm-default=all flag
- Obsolete @JvmDefaultWithCompatibility error removed from interfaces
Deprecations
- hasAnnotations flag in kotlin-metadata deprecated, replaced with JVM-only hasAnnotationsInBytecode
- CreateNSStringFromKString and CreateKStringFromNSString hidden or removed for Kotlin/Native
- Declaration of atomic properties marked with @PublishedApi now errors instead of warns
Recent Releases
All releases →
v2.5.0-Beta2
Oct 21, 2026
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v2.4.21
Oct 8, 2026
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v2.4.21-RC
Sep 30, 2026
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v2.5.0-Beta1
Sep 23, 2026
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v2.4.20
Sep 7, 2026
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v2.4.20-RC3
Sep 2, 2026
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v2.4.20-RC2
Aug 26, 2026
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v2.4.20-RC
Aug 12, 2026
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v2.4.20-Beta2
Jul 22, 2026
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v2.4.10
Jul 14, 2026
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v2.4.10-RC2
Jul 7, 2026
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