KaptExecution Failure in Android Projects

The "A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptExecution" error is a common but frustrating issue encountered by Android developers when using Kotlin's annotation processing tool (kapt). This error typically manifests with vague error messages, making it difficult to pinpoint the exact cause.

Common Causes and Solutions

1. JDK Configuration Issues

WARNING

Using an incompatible JDK version is one of the most frequent causes of KaptExecution failures.

Solution: Use Embedded JDK in Android Studio

1. Go to File → Settings → Build, Execution, Deployment → Build Tools → Gradle
2. Under Gradle JDK, select Embedded JDK option
3. Sync your project

On macOS:

• Android Studio → Preferences → Build, Execution, Deployment → Build Tools → Gradle

Alternatively, you can manually configure JDK 11:

// In your project's gradle.properties
org.gradle.jvmargs=-Xmx1536m

2. Room Database Library Conflicts

DANGER

Using outdated Room persistence library versions or mixing incompatible versions causes KaptExecution failures.

Outdated (Problematic) Configuration:

// DON'T USE - These are outdated
implementation "android.arch.persistence.room:runtime:1.1.1"
kapt "android.arch.persistence.room:compiler:1.1.1"

Current (Recommended) Configuration:

// Updated Room configuration (as of 2024)
def room_version = "2.6.1"
implementation "androidx.room:room-runtime:$room_version"
implementation "androidx.room:room-ktx:$room_version"
kapt "androidx.room:room-compiler:$room_version"

// For M1 Mac users, add this SQLite dependency:
kapt "org.xerial:sqlite-jdbc:3.45.1.0"

3. Kotlin Version Incompatibility

TIP

Keep your Kotlin plugin version synchronized across all dependencies to avoid conflicts.

Check your project-level build.gradle:

buildscript {
    ext.kotlin_version = '1.9.0' // Use latest stable version
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

4. Hilt Dependency Injection Issues

WARNING

Hilt dependencies must use consistent versions across all configurations.

Proper Hilt Configuration:

// Dagger - Hilt
implementation "com.google.dagger:hilt-android:2.50"
kapt "com.google.dagger:hilt-android-compiler:2.50"
kapt "androidx.hilt:hilt-compiler:1.2.0"
implementation "androidx.hilt:hilt-navigation-compose:1.2.0"

// Hilt for testing - MUST use same version
androidTestImplementation "com.google.dagger:hilt-android-testing:2.50"
kaptAndroidTest "com.google.dagger:hilt-android-compiler:2.50"

5. Build Caches and Permissions Issues

Windows-specific solution: If you encounter permission errors on Windows, especially after switching user accounts:

# Delete the Gradle cache directory
rm -rf C:\Users\[username]\.gradle\caches

# Or change ownership of the Gradle directory
# through Windows security properties

Debugging Techniques

When encountering KaptExecution failures, always check the detailed error logs:

# Run with stacktrace for detailed error information
./gradlew build --stacktrace

# Run with info for more log output
./gradlew build --info

# Run specific task without kapt to isolate the issue
./gradlew build -x kaptKotlin -x kaptTestKotlin

Common Room-Specific Issues

1. Missing Primary Key:

// DON'T FORGET @PrimaryKey annotation
@Entity(tableName = "items")
data class Item(
    @PrimaryKey(autoGenerate = true) // This is required
    val id: Int,
    val name: String
)

2. Enum Handling:

// Store enum as Int to avoid issues
@Entity(tableName = "flower_table")
data class Flower(
    @PrimaryKey(autoGenerate = true) val id: Int,
    val name: String,
    val color: Int // Store enum ordinal instead of enum type
)

// Usage
val flower = Flower(4, "tulip", Color.BLUE.ordinal)

File Permissions and Cache Issues

If you suspect file permission issues (common on Windows and multi-user systems):

1. Delete the .gradle directory in your project
2. Clean and rebuild the project
3. Check file ownership if you've switched user accounts

Proactive Prevention

1. Regular Dependency Updates:

   • Use Android Studio's File → Project Structure → Suggestions to identify outdated dependencies
   • Keep all related dependencies synchronized (Room, Hilt, Kotlin)

2. Version Consistency:

   • Ensure all dependencies from the same library family use identical versions
   • Avoid mixing AndroidX and legacy Android Support libraries

3. M1 Mac Considerations:

   • Always include the SQLite JDBC dependency for Room on M1 Macs
   • Consider using the latest Room alpha versions for better M1 compatibility

Conclusion

The KaptExecution failure typically stems from version incompatibilities, configuration issues, or environment problems. By maintaining consistent dependency versions, using the correct JDK configuration, and following the recommended solutions for your specific setup, you can resolve this error and prevent it from recurring in your Android projects.

INFO

Remember that build errors often provide limited information. Always use --stacktrace to get detailed error messages that can help pinpoint the exact cause of the failure.