kotlinx.serialization: kotlin Multiplatform module: build errors

I tried using kotlinx.serialization in a kotlin multiplatform project in a commons module with some small model classes looking like the following:


@Serializable
open class Document {
    var _id: String? = null
    var _rev: String? = null
}

@Serializable
class User : Document() {

    var username: String = ""
    var email: String = ""
    var rollen: List<UserRoles> = emptyList()

    companion object {
        val TYPE = "User"
    }
}

But when building via command-line I get following errors:

Unresolved reference: kotlinx
Cannot access 'Serializable': it is internal in 'kotlin.io'
This class does not have a constructor

Its mentioned in the description that it should work with the kotlinx-serialization-runtime-common dependency which I am using. The plugin should stay the same as far as I read.

I am using kotlin 1.2.21, but already tried 1.2.20, 1.2.10 with the same results. Gradle 4.4.1

About this issue

Original URL
State: closed
Created 6 years ago
Reactions: 11
Comments: 17 (10 by maintainers)

Most upvoted comments

I received the same error message (“Cannot access ‘Serializable’: it is internal in ‘kotlin.io’”), but only because I forgot the import kotlinx.serialization.*. IntelliJ did not suggest to add this import automatically, so I first assumed some configuration issue. Maybe it helps someone arrivin here via Google.

+37

matthiaswelz on Aug 8, 2019

I get rid of that error by import java.io.Serializable. I hope it helps.

MajidHJ on Jan 15, 2020

You need to apply plugin: 'kotlinx-serialization' in platform buildscript too

sandwwraith on Jan 31, 2018

@fisiodes Try to add import kotlinx.serialization.* to your file

sandwwraith on Dec 28, 2020

The dependency tree by gradle is the following:

+--- org.jetbrains.kotlin:kotlin-stdlib-common:1.2.21
\--- org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:0.4
     \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.2.10 -> 1.2.21

IntelliJ shows them as known but gradlew throws those errors… However in the tests of the jvm-target kotlinx isn’t known . Only when adding an additional dependency to kotlinx-serialization-runtime there. It looks like the common dependency isn’t grabbed correctly.

I setup a minimal testproject here: https://github.com/daberni/kotlinx.serialization_test

Another issue which came up is, that Mapper isn’t recognizing @Optional correctly. Parsing JSON works successfully, but working with a map where the key is missing doesn’t work.

daberni on Jan 31, 2018

If anyone else runs into this issue make sure have enableFeaturePreview('GRADLE_METADATA') in settings.gradle

jeremyrempel on Aug 6, 2019

Thanks for the help 👍

It would be nice if the documentation could explain these steps in more detail. Probably I will make a PR for this 😉

daberni on Jan 31, 2018