Android Studio could not build Flutter App APK after migration

Question

After the migration, my project would run but the command Flutter build apk --release fails giving me this error:

* What went wrong:
A problem occurred evaluating project ':app'.
> Could not get unknown property 'kotlin_version' for object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

BUILD FAILED in 3s
Running Gradle task 'assembleRelease'...
Gradle task assembleRelease failed with exit code 1

Here are the files involved

app/build.gradle:

plugins {
        id "com.android.application"
        id "kotlin-android"
        id "dev.flutter.flutter-gradle-plugin"
    }


def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}


def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}


android {
    namespace "my.name.space"
    compileSdkVersion flutter.compileSdkVersion
    ndkVersion flutter.ndkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "my.application.id"
        // You can update the following values to match your application needs.
        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration.
        minSdkVersion flutter.minSdkVersion
        targetSdkVersion flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

settings.gradle:

pluginManagement {
    def flutterSdkPath = {
        def properties = new Properties()
        file("local.properties").withInputStream { properties.load(it) }
        def flutterSdkPath = properties.getProperty("flutter.sdk")
        assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
        return flutterSdkPath
    }()

    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")

    repositories {
        google()
        mavenCentral()
        gradlePluginPortal()
    }
}

plugins {
    id "dev.flutter.flutter-plugin-loader" version "1.0.0"
    id "com.android.application" version "7.3.0" apply false
    id "org.jetbrains.kotlin.android" version "1.7.10" apply false
}

include ":app"

android/build.gradle:

allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

tasks.register("clean", Delete) {
    delete rootProject.buildDir
}

I really cannot find a solution to this, since the buildscript block has been removed, all the previous solutions are inapplicable. I tried to delete android folder and then use create command. Also tried to delete only settings.gradle and create command. Can anyone help me?

Answer 1

I cannot reproduce your problem, but i had this problem too in the past (and i spent a couple of hours to resolve).

I think you're missing in android/build.gradle, at the start, the ext declaration

ext {
    compileSdkVersion = 34                // or latest
    targetSdkVersion = 34                // or latest
    appCompatVersion = "1.4.2"           // or latest
}