Resolving 'namespace not specified' error in Android Studio after AGP 8 upgrade

Problem Statement

When upgrading Android projects to Android Studio Flamingo and Android Gradle Plugin (AGP) 8.0.0+, developers encounter this critical build error:

Namespace not specified. Please specify a namespace in the module's build.gradle file like so:

android {
    namespace 'com.example.namespace'
}

This occurs because AGP 8+ requires the namespace attribute in each module's build.gradle file. Older projects relied on the package attribute in AndroidManifest.xml, which AGP 8 no longer uses for resource identification. The challenge worsens in projects with multiple modules (like Ionic/Capacitor setups), where dependencies might not yet declare their own namespaces.

Root Causes

• AGP 8+ mandates explicit namespace declarations in build.gradle files
• Migrated projects retain legacy AndroidManifest.xml package attributes
• Third-party plugins/modules without namespace declarations break builds
• Incomplete AGP migration using the official Upgrade Assistant

Recommended Solutions

Solution 1: Add namespace resolution script (Top-level Gradle)

Add this code to your project-level build.gradle (android/build.gradle) to automatically configure namespaces for modules:

allprojects {
    repositories {
        google()
        mavenCentral()
    }
    subprojects {
        afterEvaluate { project ->
            if (project.hasProperty('android')) {
                project.android {
                    if (namespace == null) {
                        // Use project group or module name as namespace
                        namespace project.group ?: "com.temp.${project.name.replace('-', '_')}"
                    }
                }
            }
        }
    }
}

For Kotlin DSL (build.gradle.kts)

allprojects {
    repositories {
        google()
        mavenCentral()
    }
    subprojects {
        afterEvaluate {
            if (plugins.hasPlugin("com.android.application") || 
                plugins.hasPlugin("com.android.library")) {
                extensions.findByType<com.android.build.gradle.BaseExtension>()?.apply {
                    if (namespace == null) {
                        namespace = name
                    }
                }
            }
        }
    }
}

How This Works

1. Processes all subprojects/modules after evaluation
2. Checks if the module has an Android plugin applied
3. Sets missing namespaces using either:
   • Existing group property (common in libraries)
   • Generated temporary namespace based on module name
4. Executes during Gradle configuration phase

Solution 2: Manual namespace configuration

For individual modules, declare the namespace in their module-level build.gradle:

android {
    namespace 'com.example.yourapp'  // Add this line
    
    compileSdk 34
    defaultConfig {
        applicationId "com.example.yourapp"
        // Other configurations...
    }
}

Migrating from AndroidManifest.xml

1. Open AndroidManifest.xml
2. Find the package attribute:

   <manifest xmlns:android="http://schemas.android.com/apk/res/android" 
       package="com.yourapp.package">

3. Copy this value to namespace in build.gradle
4. Remove the package attribute from AndroidManifest.xml

Solution 3: Use AGP Upgrade Assistant (First-Time Migration)

TIP

Use this approach if you're migrating to AGP 8.0+ for the first time

1. Open Android Studio ≥ Flamingo (2022.2.1)
2. Go to Help > AGP Upgrade Assistant
3. Follow on-screen prompts
4. Accept recommended changes for dependencies
5. Sync Gradle files (Sync Now in notification bar)

Special Cases

Ionic/Capacitor Projects

1. Confirm all Capacitor plugins are updated
2. Run:

   npm install
   npx cap sync android

3. If issues persist:

   npx jetify

Handling Old Plugins

For third-party plugins without AGP 8 support:

android {
    // Conditional compatibility for AGP 7/8
    if (getGradle().getGradleVersion().substring(0, 1).toInteger() >= 8) {
        namespace "com.something.plugin"
    }
}

Fix Verification

After applying these solutions:

1. Clean build: ./gradlew clean
2. Rebuild project: ./gradlew assembleDebug
3. Invalidate Android Studio caches:
   • File > Invalidate Caches / Restart
   • Select Invalidate and Restart

WARNING

Temporary namespaces (like com.temp.*) are stopgap solutions. Contact plugin maintainers to add proper namespace declarations.

Additional Tips

1. Always back up build.gradle before modifications
2. Use version control to track configuration changes
3. Confirm plugins support AGP 8+ before upgrading
4. Replace deprecated compile with implementation in dependencies
5. Resolve V1/V2 signing conflicts if they appear post-upgrade

Migrating to the new namespace system ensures compatibility with modern Android build tools and prevents resource conflicts. For large projects, combine the automated Gradle script with targeted manual fixes for optimal results.