Android App Bundle (AAB) format used instead of APK

Google Play has required Android App Bundle (AAB) format for new app submissions since August 2021 and for all app updates since November 2021. Submitting an APK to Google Play for a new app returns an immediate upload error in Play Console — no review occurs, no exception is granted. The build toolchain distinction is subtle: ./gradlew assembleRelease produces an APK; ./gradlew bundleRelease produces an AAB. Fastfile lanes that use gradle(task: 'assemble') are wrong for Play Store submission. The AAB requirement also means developers must use Google Play App Signing — direct APK signing keys can no longer be used for Play distribution.

Update the Fastfile release lane to produce AAB output:

# fastlane/Fastfile
lane :release do
  gradle(
    task: 'bundle',           # NOT 'assemble'
    build_type: 'Release'
  )
end

For EAS Build, verify eas.json does not override the default:

"build": {
  "production": {
    "android": {
      "buildType": "app-bundle"  // default; explicitly set to avoid accidental APK
    }
  }
}

For manual builds, run ./gradlew bundleRelease — the output is android/app/build/outputs/bundle/release/app-release.aab. Upload this file to Play Console under Production → Create new release. Enroll in Google Play App Signing if not already done — required for AAB distribution.