Applying the plugin 'kotlin-android' in an Instant App results in "null cannot be cast to non-null type com.android.build.gradleBasePlugin"

Question

I've been trying to combine the newly publicly released Android Instant Apps with the Kotlin programming language. After creating my project using the following (standard?) setup, I get an Error with the message "null cannot be cast to non-null type com.android.build.gradle.BasePlugin" when I try to build the application. Using Kotlin works fine with standard 'com.android.application' modules; the Error is thrown only when I try to use it within an Instant App module.

Top-level build.gradle:

buildscript {

    repositories {
        maven { url 'https://maven.google.com' }
        jcenter()
    }

    dependencies {
        classpath "com.android.tools.build:gradle:3.0.0-alpha1"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.1.2-4"
    }
}

// ...

app module build.gradle, in which Kotlin does work:

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android' // This will work.

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"


    defaultConfig {
        // ...
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation project(':feature')
    implementation project(':base')
}

base module build.gradle, in which Kotlin does not work:

apply plugin: 'com.android.feature'
apply plugin: 'kotlin-android' // This won't work.

android {

    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    baseFeature true
    defaultConfig {
        // ...
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    feature project(':tracker')
    compile 'com.android.support:appcompat-v7:25.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'

    // Kotlin standard library.
    compile "org.jetbrains.kotlin:kotlin-stdlib:${gradleKotlinVersion}"
}

instantapp module build.gradle:

apply plugin: 'com.android.instantapp'

dependencies {
    implementation project(':feature')
    implementation project(':base')
}

feature module build.gradle:

apply plugin: 'com.android.feature'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        // ...
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    implementation project(':base')
    testCompile 'junit:junit:4.12'
}

Again, the app module compiles without issues with this configuration; on the other hand, Android Studio / Gradle gives me this strange "null cannot be cast to non-null type com.android.build.gradle.BasePlugin" error message, with the suggestions to re-download dependencies and sync the project (done) or restart Android Studio.

Are Instant Apps actually compatible with the Kotlin programming language ? I'm looking forward to your answers :)

PS: I use Android Studio 3.0 Canary 1, with the latest updates installed from the Canary Channel for Build tools etc. My Kotlin plugin should be up-to-date as well.

Answer 1

This is addressed in Kotlin plugin v1.1.2-5. Please update your version and try again.

For reference, the issue with previous plugin versions is being tracked here:

38393607 | Issue building Instant apps with Kotlin enabled