Kotlin v2.3.20-RC released!

NewsBot · 19 February 2026 13:25

Kotlin v2.3.20-RC has been released.

Changelog

Backend. Wasm

KT-82649 K/Wasm: Rewrite StringBuilder to use JsString

KT-83995 K/Wasm: 2.3.0 → 2.3.20-Beta1 degradation in arrow tests

KT-83839 K/Wasm: CMP. Load time on Safari significantly increased with Kotlin = 2.3.20-Beta1

Compiler

KT-83372 compileDebugKotlinAndroid hangs in 2.3.0 with SQLDelight

KT-83849 False-positive NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS for Optional.orElse(null) call

KT-84192 “Member overrides different ‘@Throws’ filter from” caused by overriding in different module

KT-83697 Native: increased bitcode produced with enabled safe casts

KT-83984 Data races around kotlinx.serialization plugin protobuf extensions registration

KT-83031 K2: unstable resolution of EnhancedNullability from type-use NotNull in presence of unused code

KT-83824 Delegated property in Gradle DSL fails to compile

KT-81700 flaky overload resolution behaviors (false-positive errors, different final candidates, compile-time failures)

KT-78443 Refactor session component initialization for multi-target compilation

Compose compiler

b/481953005, b/481769383 Cache stability inference results during session

b/481735904 Fix Com…

Link: Release Kotlin 2.3.20-RC · JetBrains/kotlin · GitHub