Issues

• parseToJsonElement accepts [1]2] as [1,2]

  bugreproduced
  Kotlin/kotlinx.serialization#3289 · Filter by author sh-cho opened on Oct 7, 2026
  2

• Protobuf.decodeFromByteArray accepts nullable types but doesn't support them

  bugprotobufreproduced
  Kotlin/kotlinx.serialization#3277 · Filter by author LouisCAD opened on Sep 28, 2026
  3

• Default (non-lenient) Json accepts unescaped control characters (U+0000–U+001F) inside strings

  Kotlin/kotlinx.serialization#3276 · Filter by author ziyadmansy opened on Sep 27, 2026
  1

  

• Document requirement to flush() Sink when using Json.encodeToSink

  docs needed
  Kotlin/kotlinx.serialization#3271 · Filter by author solonovamax opened on Sep 13, 2026
  6

  

• SerializationException: Report fully qualified class name when class is not registered

  Kotlin/kotlinx.serialization#3268 · Filter by author fzhinkin opened on Sep 9, 2026
  1

• JsonPrimitive.longOrNull returns a wrapped value for integers above 2^64

  bug
  Bug

  Kotlin/kotlinx.serialization#3267 · Filter by author jarohen opened on Sep 9, 2026
  1

  

• Also re-throw SerializationException as JsonDecodingException

  feature
  Kotlin/kotlinx.serialization#3262 · Filter by author NichtStudioCode opened on Sep 8, 2026
  3

  

• Long numbers are truncated when serializing JsonElement

  bugjsonreproduced
  Bug

  Kotlin/kotlinx.serialization#3257 · Filter by author SPC-code opened on Sep 4, 2026
  13

  

• Get rid of NamedValueEncoder/Decoder in TreeJson*

  jsonperformance
  Kotlin/kotlinx.serialization#3249 · Filter by author qwwdfsad opened on Sep 2, 2026
  

• Supported hook for substituting serializers during a (de)serialization operation

  Kotlin/kotlinx.serialization#3243 · Filter by author kamalnayan04 opened on Aug 31, 2026
  9

• Properties marked with @EncodeDefault in data objects are ignored

  docs needed
  Kotlin/kotlinx.serialization#3214 · Filter by author RaySmith-ttc opened on Jul 4, 2026
  3

  

• CBOR @ValueTags is not encoded with primitive types

  cbor
  Kotlin/kotlinx.serialization#3198 · Filter by author jksiezni opened on May 17, 2026
  1

  

• More granular control of class discriminator at use site

  feature
  Kotlin/kotlinx.serialization#3187 · Filter by author geoffliu opened on Apr 24, 2026
  4

• Add @JvmStatic to generated serializer() in Companion

  featurewaiting for clarification
  Kotlin/kotlinx.serialization#3185 · Filter by author cdprete opened on Apr 23, 2026
  4

• Decoding sealed inline class child wrapping Map tries to decode class discriminator

  bugreproduced
  Kotlin/kotlinx.serialization#3172 · Filter by author tadfisher opened on Apr 3, 2026
  1

• Rework tags/paths in JsonTreeDecoder

  Kotlin/kotlinx.serialization#3170 · Filter by author sandwwraith opened on Apr 2, 2026
  1

  

• Global setting to enforce usage of @ProtoNumber

  feature
  Kotlin/kotlinx.serialization#3164 · Filter by author vanniktech opened on Mar 21, 2026
  1

• Make AbstractPolymorphicSerializer.findPolymorphicSerializerOrNull take a SerializersModule directly

  feature
  Kotlin/kotlinx.serialization#3157 · Filter by author Laxystem opened on Mar 3, 2026
  1

• Add a annotation for fallback polymorphic/enum types

  feature
  Kotlin/kotlinx.serialization#3131 · Filter by author ansman opened on Dec 19, 2025
  3

• Expose encodeToDynamic and decodeFromDynamic to WASM js

  feature
  Kotlin/kotlinx.serialization#3129 · Filter by author SalomonBrys opened on Dec 18, 2025

• Allow JsonNames on classes

  feature
  Kotlin/kotlinx.serialization#3127 · Filter by author ansman opened on Dec 15, 2025
  6

• Non-nullable serializer used for nullable field inside generic sealed class, causing null pointer exception.

  bugreproduced
  Kotlin/kotlinx.serialization#3118 · Filter by author availe opened on Nov 25, 2025

• ProtoBuf cannot deserialize the Map from rs/prost if its value equals the default value

  Kotlin/kotlinx.serialization#3113 · Filter by author zhangz1han opened on Nov 17, 2025
  1

• Classes loaded to diffrent class-loaders have equal serial descriptor

  Kotlin/kotlinx.serialization#3110 · Filter by author kunyavskiy opened on Nov 12, 2025
  4

• Consider unifying serial names of SealedClassSerializer and PolymorphicClassSerializer

  Kotlin/kotlinx.serialization#3104 · Filter by author sandwwraith opened on Nov 4, 2025
  1