No signature of method android() error in Gradle

This error occurs when there's a syntax or configuration issue in your Android project's build.gradle file. The error message is generic and doesn't point to the specific problem, making it challenging to debug.

Common Causes and Solutions

1. Deprecated Kotlin Android Extensions

If you've recently updated Kotlin, the Android Extensions plugin may be causing issues:

// Remove these from your build.gradle
apply plugin: 'kotlin-android-extensions'

android {
    // Remove this block
    androidExtensions {
        experimental = true
    }
}

WARNING

Kotlin Android Extensions were deprecated in Kotlin 1.4.21+. Use view binding or data binding instead.

2. Proguard Configuration Issues

Several users reported issues with useProguard:

buildTypes {
    release {
        minifyEnabled true
        // Remove or comment out useProguard
        // useProguard true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

3. Namespace Conflicts

If you've recently added namespace configuration:

android {
    // Remove namespace line if causing issues
    // namespace 'com.example.app'
    
    // Ensure package is set in AndroidManifest.xml instead
}

<!-- AndroidManifest.xml -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.app">
</manifest>

4. Duplicate Configuration Blocks

Check for accidentally duplicated configuration blocks:

android {
    // Remove duplicate blocks like:
    // compileOptions {
    //     sourceCompatibility JavaVersion.VERSION_1_8
    //     targetCompatibility JavaVersion.VERSION_1_8
    // }
}

5. Syntax Errors

Common syntax mistakes include:

• Method name typos (compilpepeeSdkVersion instead of compileSdkVersion)
• Incorrect line breaks in method calls
• Missing commas or parentheses

Debugging the Actual Error

Since the error message is generic, you need to get the actual error:

./gradlew :app:assembleDebug --stacktrace

or

./gradlew clean && ./gradlew :app:bundleRelease --info

Look through the output for the real error message that's being masked by the generic error.

Complete Gradle Example

Here's a working build.gradle example for reference:

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

android {
    compileSdkVersion 33
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.app"
        minSdkVersion 21
        targetSdkVersion 33
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

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

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

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.6.1'
    implementation 'androidx.core:core-ktx:1.10.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
}

Additional Troubleshooting Steps

If the above solutions don't work:

1. Clean Gradle cache: Delete the .gradle folder in your user directory
2. Invalidate caches: In Android Studio, go to File > Invalidate Caches / Restart
3. Check JDK version: Ensure you're using a compatible 64-bit JDK
4. Update dependencies: Ensure all plugin versions are compatible

TIP

Always backup your build.gradle file before making significant changes. Comment out sections one by one to identify the problematic code.

When to Seek Further Help

If none of these solutions work, your specific issue might be unique to your project setup. Consider:

• Checking for custom plugins or unusual configurations
• Ensuring all variable names don't conflict with reserved keywords
• Verifying that all plugin versions are compatible with each other

The error is always caused by a configuration issue in your Gradle file - methodically reviewing and testing each section will eventually reveal the problem.