after updating Flutter I’m getting this error with almost every package I add to the project. For this example we’ll use the permission_handler package.

FAILURE: Build failed with an exception.

* Where:
Build file 'C:UsersUSERAppDataLocalPubCachehostedpub.devpermission_handler_android-12.0.7androidbuild.gradle' line: 43

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

So far I understand that the variable kotlin_version which used to be in build.gradle is missing. That’s because I followed the migration docs step by step which told me to delete that part.

Here’s how my build.gradle (Android) looks like now:

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
}

Here’s how the build.gradle app looks like now:

plugins {
    id "com.android.application"
    id "kotlin-android"
    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
    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 = "com.example.geo_app"
    compileSdk = 34
    ndkVersion = flutter.ndkVersion

    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId = "com.example.geo_app"
        // 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.
        minSdk = flutter.minSdkVersion
        targetSdk = 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 = "../.."
}

And here’s the 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 "1.7.20" apply false
}

include ":app"

When searching for this error, I only see people suggesting to add ext.kotlin_version = *** to the buildscript block, meanwhile that block does not exist anymore.