Hello! When I try to build, I get this error: `Your current kotlinx.serialization core version is t...

# multiplatform

[Sebastien Leclerc Lavallee]

Hello! When I try to build, I get this error:
Your current kotlinx.serialization core version is too low, while current Kotlin compiler plugin 1.4.0 requires at least 1.0-M1-SNAPSHOT. Please update your kotlinx.serialization runtime dependency.

The problem is, I never updated to Kotlin 1.4. My Kotlin used for dependencies is 1.3.70. I did came across a warning yesterday that sais something like: Common module has an external compiler that use Kotlin 1.4
Does that ring a bell to someone? The “only” thing I did was to update from gradle 5.6.X to 6.5, but I doubt it had that kind of repercussion. Thanks 🙂

[Marc Knaup]

Is this a Gradle build or does the IDE build it without Gradle?

[Sebastien Leclerc Lavallee]

Gradle build

[Marc Knaup]

That’s weird then. kotlin("multiplatform") version "1.3.72" shouldn’t use a 1.4 compiler 😅

[Sebastien Leclerc Lavallee]

I do not explicitly set version for multiplatform plugin because I have this error: Plugin request for plugin already on the classpath must not include a version

And this is my root dependencies:

dependencies {
        classpath(Deps.android_gradle_plugin)
        classpath("org.jetbrains.kotlin:kotlin-serialization:${Versions.kotlin}")

        classpath(kotlin("gradle-plugin", Versions.kotlin))
        classpath(Deps.buildKonfig)

        classpath(Deps.Google.services)
    }

[Marc Knaup]

Versions.kotlin it should be then.

But Deps.buildKonfig may upgrade it transitively to 1.4.0?

[Marc Knaup]

You could use a ./gradlew build --scan to create a build scan and then explore the build dependencies on the web to see what dependency causes the upgrade to 1.4.0

[Sebastien Leclerc Lavallee]

Thanks for the tip!

Versions.kotlin point to 1.3.70 so it shouldn’t be that. But maybe buildKonfig

[Sebastien Leclerc Lavallee]

Well, that buildKonfig was causing problem 😅 Thanks for the help!