Kotlin v2.3.20-Beta1 released!

NewsBot · 8 January 2026 13:25

Kotlin v2.3.20-Beta1 has been released.

Changelog

Analysis API. FIR

New Features

KT-78090 Implement stubs support for new conditional returns and holdsIn contracts

Fixes

KT-80485 False positive UNRESOLVED_REFERENCE on nested interface from super-super class in the super type position inside an anonymous object

KT-82948 ‘FirRegularClass’ expected as a containing declaration, got ‘FirTypeAliasImpl’

KT-82057 K2. Cannot infer type parameter ‘R’ in Ktor routing post() function with explicit response type

KT-82772 Flaky false positive deprecation warning on PersistentMap.put in Kotlin repo in IDE mode

KT-76487 StdLibSourcesLazyDeclarationResolveTestGenerated.testWrappedInt is unstable

KT-82618 Various tests are failing with NPE in kt-master after updating the compiler on 19.11.25

KT-82076 Error querying members of JavaClass created for SymbolLightClassForAnnotationClass during library analysis

KT-71596 Include Js/Wasi checkers in AbstractLLFirDiagnosticsCollector

KT-82085 No OUTER_CLASS_ARGUMENTS_REQUIRED on type parameter bound in IDE

KT-81873 Provide a way of including traces in phase JFR events

KT-71929 Consider leaving the non-post-compute version at EnhancementSymbolsCache.enhancedFunctions

Analysis API. Infrastructure

KT-65140 LL FIR: Implement AbstractFirPsiJsDiagnosticTest…

Link: Release Kotlin 2.3.20-Beta1 · JetBrains/kotlin · GitHub