Fixing Build Errors: Upgrade Android Gradle Plugin

Experiencing build errors in your Flet projects? You're not alone! This comprehensive guide will walk you through resolving those pesky issues by upgrading your Android Gradle Plugin (AGP). We'll break down the error messages, explain why the upgrade is necessary, and provide a step-by-step solution to get your builds running smoothly again. Let's dive in!

Understanding the Problem: Why Upgrade Your Android Gradle Plugin?

If you've encountered an error message similar to the one below, it's a clear indication that your AGP version is outdated and needs an upgrade:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:checkReleaseAarMetadata'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
   > 2 issues were found when checking AAR metadata:

      1.  Dependency 'androidx.core:core-ktx:1.17.0' requires Android Gradle plugin 8.9.1 or higher.

          This build currently uses Android Gradle plugin 8.6.1.

      2.  Dependency 'androidx.core:core:1.17.0' requires Android Gradle plugin 8.9.1 or higher.

          This build currently uses Android Gradle plugin 8.6.1.

This error arises because newer libraries and dependencies, such as androidx.core:core-ktx:1.17.0 and androidx.core:core:1.17.0, require a more recent version of the AGP (in this case, 8.9.1 or higher). The AGP is the backbone of the Android build process, responsible for compiling resources, packaging code, and ultimately creating your APK. Staying up-to-date with the AGP ensures compatibility with the latest libraries, features, and performance improvements.

Key Takeaway: An outdated AGP can lead to build failures and prevent you from leveraging the latest advancements in the Android ecosystem. Keeping it updated is crucial for a seamless development experience.

Step-by-Step Solution: Bumping Your Android Gradle Plugin

Fortunately, upgrading your AGP is a straightforward process. Follow these steps to resolve your build errors and get your project back on track:

Step 1: Identify the Required Gradle Version

The AGP version is intrinsically linked to the Gradle version. In the error message above, it's stated that AGP 8.9.1 or higher is needed. To determine the compatible Gradle version, consult the official Android Gradle plugin release notes or the Gradle compatibility matrix. Generally, AGP 8.9.1 requires Gradle 8.11.1 or higher. Using a compatible Gradle version ensures that all the build processes work harmoniously.

Step 2: Modify gradle-wrapper.properties

The gradle-wrapper.properties file, located in your project's gradle/wrapper directory, specifies the Gradle version used for your build. You'll need to update the distributionUrl property to point to the required Gradle distribution. Open gradle-wrapper.properties and modify the distributionUrl line as follows:

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-bin.zip

Important: Ensure you use the correct Gradle version based on the AGP requirements. In this example, we're using Gradle 8.11.1, which is compatible with AGP 8.9.1.

Step 3: Update build.gradle (Project Level)

Next, you need to update the build.gradle file at the project level (the one in the root directory of your project). This file contains configurations that apply to the entire project. Locate the build.gradle file and update the buildscript and dependencies blocks as follows:

buildscript {
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:8.9.1' // or higher
        classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.9.22' // Or higher, depending on your kotlin version
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

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

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

Key Changes:

• classpath 'com.android.tools.build:gradle:8.9.1': This line specifies the AGP version. Make sure to use the desired version (8.9.1 or higher).
• classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.9.22': Ensure your Kotlin Gradle plugin version is compatible with the AGP version. Check the compatibility matrix for the recommended version.

Step 4: Update build.gradle (App Level)

Now, update the build.gradle file at the app level (usually located in the app directory). This file contains configurations specific to your application module. Open the build.gradle file and make the following changes:

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
}

android {
    namespace 'your.package.name' // Replace with your package name
    compileSdkVersion 34 // or higher

    defaultConfig {
        applicationId "your.package.name" // Replace with your package name
        minSdkVersion 24
        targetSdkVersion 34
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_17
        targetCompatibility JavaVersion.VERSION_17
    }
    kotlinOptions {
        jvmTarget = '17'
    }
    // Add this block
    lint {
        abortOnError false
    }
}

dependencies {

    implementation 'androidx.core:core-ktx:1.12.0' // Or higher
    implementation 'androidx.appcompat:appcompat:1.6.1'
    implementation 'com.google.android.material:material:1.11.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
}

Key Changes and Considerations:

• namespace 'your.package.name': Add your application's package name here.
• compileSdkVersion 34: Set your compileSdkVersion to the latest stable API level (34 or higher).
• targetSdkVersion 34: Set your targetSdkVersion to the same value as compileSdkVersion.
• sourceCompatibility JavaVersion.VERSION_17 and targetCompatibility JavaVersion.VERSION_17: Ensure you are using Java 17 or higher.
• kotlinOptions { jvmTarget = '17' }: Set the JVM target to 17 to match the Java version.
• implementation 'androidx.core:core-ktx:1.12.0': Update androidx.core:core-ktx and other dependencies to compatible versions. Check for the latest stable releases.
• lint { abortOnError false }: Adding this block is crucial. AGP versions 8.0 and higher are stricter with linting. Setting abortOnError to false prevents the build from failing due to linting errors. This allows you to address linting issues gradually without halting your development process.

Step 5: Sync Gradle and Clean Project

After making these changes, sync your Gradle files. In Android Studio, you can do this by clicking