Kotlin compile "ERROR: The Android Gradle plugin supports only Kotlin Gradle plugin version 1.3.0 and higher." but no kotlin_version in build.gradle?

Question

I tried cloning and building this project, https://github.com/mitrejcevski/ui-testing, but upon opening it in Android Studio, I get the following build error:

ERROR: The Android Gradle plugin supports only Kotlin Gradle plugin version 1.3.0 and higher.
The following dependencies do not satisfy the required version:
root project 'ui-testing' -> org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.21
Affected Modules: app

However, when I click the 'app' hyperlink I am led to the module-level build.gradle file, which reads

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "nl.jovmit"
        minSdkVersion 19
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

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

    productFlavors {
        mock {
            flavorDimensions "default"
        }
        prod {
            flavorDimensions "default"
        }
    }

    android.variantFilter { variant ->
        if (variant.buildType.name == 'release' && variant.getFlavors().get(0).name == 'mock') {
            variant.setIgnore(true)
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation "com.android.support:appcompat-v7:$support_version"
    implementation "com.android.support:design:$support_version"
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.21'

    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

    testImplementation 'junit:junit:4.12'
}

Unlike the accepted answer of ERROR: The Android Gradle plugin supports only Kotlin Gradle plugin version 1.3.0 and higher, I don't see any ext.kotlin_version anywhere in the Gradle file.

I do see this warning, though, that kotlin-stdlib-jre7 is deprecated:

However, I tried changing this but still get the same error. I've also tried adding the line

implementation 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.21'

to dependencies (as seen in the screenshot above), but that also didn't prevent the error.

Any idea how to fix this? I suspect that the outdated Kotlin version is a 'sub-dependency' of one of the dependencies here, but haven't been able to figure out which one.

Answer 1

Define your ext.kotlin_version

Your project level build.gradle should look like this.

buildscript {
    ext.kotlin_version = '1.2.51'
    ext.android_plugin_version = '3.2.1'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:$android_plugin_version"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}