K Manga JSON Decoding Error
Author: letmegobacktosleepCreated Aug 31, 2026Updated Sep 14, 2026
Labelsbug
Steps to reproduce
- Open K Manga / Reload manga from K Manga / Download chapter from K Manga
- Observe error message
Expected behavior
- Extension should work
Actual behavior
- Got JSON Decoding error
Suwayomi-Server version
v2.3.2344
Used database
PostgreSQL
Server operating system
Ubuntu 24.04.4 LTS
Server Desktop Environment
Gnome 46.0
Server JVM version
openjdk version "25.0.3" 2026-04-21 LTS
Used client name
Suwayomi-WebUI
Client version
r3475
Used web browser
Firefox 154.0.1 (Arm) | Firefox 154.0.1 (64bit)
Client operating system
MacOS Tahoe | Windows 11 Home 25H2
Other details
Suwayomi is being run in the latest version of docker, is an issue only with K Manga as far as I can see. I have checked on the Keiyoushi server, K Manga works as expected on Mihon and TachoyomiSY.
Error message in Docker Compose logs:
suwayomi | 08:37:23.901 [DefaultDispatcher-worker-23] ERROR suwayomi.tachidesk.graphql.mutations.MangaMutation -- Error updating manga and chapters
suwayomi | kotlinx.serialization.json.JsonDecodingException: Unexpected JSON token at offset 0: Expected beginning of the string, but got { at path: $
suwayomi | JSON input: {"isLoggedIn":true,"checkedTicketExpiredList":[{"userId":4093286,"date":"2026-08-29","isExpiredBadge":false}]}
suwayomi | at kotlinx.serialization.json.internal.JsonExceptionsKt.decodingExceptionOf(JsonExceptions.kt:48)
suwayomi | at kotlinx.serialization.json.internal.AbstractJsonLexer.fail(AbstractJsonLexer.kt:583)
suwayomi | at kotlinx.serialization.json.internal.AbstractJsonLexer.fail$default(AbstractJsonLexer.kt:582)
suwayomi | at kotlinx.serialization.json.internal.AbstractJsonLexer.consumeStringLenient(AbstractJsonLexer.kt:456)
suwayomi | at kotlinx.serialization.json.internal.AbstractJsonLexer.unexpectedToken(AbstractJsonLexer.kt:221)
suwayomi | at kotlinx.serialization.json.internal.StringJsonLexer.consumeNextToken(StringJsonLexer.kt:81)
suwayomi | at kotlinx.serialization.json.internal.StringJsonLexer.consumeKeyString(StringJsonLexer.kt:93)
suwayomi | at kotlinx.serialization.json.internal.AbstractJsonLexer.consumeString(AbstractJsonLexer.kt:372)
suwayomi | at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeString(StreamingJsonDecoder.kt:340)
suwayomi | at kotlinx.serialization.internal.StringSerializer.deserialize(Primitives.kt:131)
suwayomi | at kotlinx.serialization.internal.StringSerializer.deserialize(Primitives.kt:127)
suwayomi | at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:69)
suwayomi | at kotlinx.serialization.internal.NullableSerializer.deserialize(NullableSerializer.kt:30)
suwayomi | at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:69)
suwayomi | at kotlinx.serialization.json.Json.decodeFromString(Json.kt:149)
suwayomi | at keiyoushi.b.m.a(Unknown Source)
suwayomi | at keiyoushi.b.q.b(Unknown Source)
suwayomi | at xyz.nulldev.androidcompat.webkit.KcefWebViewProvider.evaluateJavaScript$lambda$0$0$0(KcefWebViewProvider.kt:718)
suwayomi | at android.os.Handler.handleCallback(Handler.java:981)
suwayomi | at android.os.Handler.dispatchMessage(Handler.java:99)
suwayomi | at android.os.Looper.loopOnce(Looper.java:229)
suwayomi | at android.os.Looper.loop(Looper.java:317)
suwayomi | at suwayomi.tachidesk.server.LooperThread.run(ServerSetup.kt:109)Acknowledgements
- I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
- I have checked the ongoing preview changelog of Suwayomi-WebUI and Suwayomi-Server and this bug has NOT been listed as fixed
- I have written a short but informative title (ideally less than ~100 characters).
- I have tried the troubleshooting guide described in README.md
- I have updated the (Suwayomi-WebUI and Suwayomi-Server) to the latest versions
- I have filled out all of the requested information in this form, including specific version numbers.
- I understand that Suwayomi does not have or fix any extensions, and I will not receive help for any issues related to sources or extensions.
Source: Suwayomi/Suwayomi-Server