Play Store Release — Android Native

Build a signed Android App Bundle (AAB) from a native Android (Java/Kotlin) project, ready for Google Play Store.

Before You Start — Assess the Project

Ask these questions BEFORE touching any files:

1. Gradle DSL? Check app/build.gradle vs build.gradle.kts

   • .kts → use isMinifyEnabled (with is prefix)
   • .gradle → use minifyEnabled (without is prefix)
   • NEVER mix — using the wrong property is a silent no-op (no error, no minification)

2. Existing signing config? Search for signingConfigs in the app build file

   • Already exists → Verify it reads from a properties file, don't duplicate
   • Missing → Add from scratch

3. Existing keystore? Ask the user before generating a new one

   • Already has .jks → Reuse it, skip Step 1
   • First release → Generate new keystore

4. Which libraries need ProGuard rules? Check build.gradle dependencies block:

   • Uses Retrofit/OkHttp → Add network rules
   • Uses Gson → Add serialization rules (or better: suggest migrating to kotlinx.serialization)
   • Uses kotlinx.serialization → Add @Serializable keep rules
   • Uses Room/Hilt/Dagger → No custom rules needed (compile-time code generation)
   • Only Jetpack Compose → No custom rules needed (Compose compiler handles it)

5. AGP version? Check libs.versions.toml or root build.gradle

   • AGP 8+ → Requires Java 17. Verify JAVA_HOME or org.gradle.java.home
   • AGP 7.x → Java 11 sufficient

6. Flavors? Search for productFlavors in the build file

   • Has flavors → Each flavor needs its own or a shared signing config; build command changes to bundleProdRelease etc.
   • No flavors → Single release config

Workflow

Step 1 — Generate Upload Keystore

keytool -genkeypair \
  -alias upload \
  -keyalg RSA -keysize 2048 \
  -validity 10000 \
  -storetype PKCS12 \
  -keystore upload-keystore.jks

Critical details:

• -validity 10000 = ~27 years. Google requires validity beyond Oct 22 2033.
• -storetype PKCS12 — avoids JKS migration warnings. But with PKCS12, store password and key password must be identical. keytool silently uses the store password for the key. Different passwords → signing fails later with misleading "Cannot recover key" error.
• Store the .jks outside the project. Recommended: ~/.android/keystores/ or a secrets manager.

Step 2 — Create Credentials File

Create keystore.properties in the project root (must NOT be committed):

storePassword=<password>
keyPassword=<same-password-as-store>
keyAlias=upload
storeFile=<absolute-or-relative-path-to-upload-keystore.jks>

Add to .gitignore:

keystore.properties
*.jks
*.keystore
local.properties

Step 3 — Configure Signing in Gradle

Claude knows Gradle signing config syntax. These are the traps:

• isMinifyEnabled vs minifyEnabled: KTS requires the is prefix. Groovy does NOT. Wrong prefix = silent no-op — build succeeds, APK is unminified, 3x larger, and exposes source code. No error, no warning. This is the #1 Android release mistake.
• isShrinkResources requires isMinifyEnabled: Resource shrinking without code minification silently does nothing. Always set both together.
• signingConfigs before buildTypes: Gradle evaluates blocks in declaration order. Referencing a signingConfig before it's declared → build error.
• rootProject.file() vs project.file(): keystore.properties lives in project root. rootProject = project root. project = app/ module. Wrong root = file not found silently, null properties at build time.

Kotlin DSL (app/build.gradle.kts)

import java.util.Properties
import java.io.FileInputStream

val keystoreProperties = Properties().apply {
    val file = rootProject.file("keystore.properties")
    if (file.exists()) load(FileInputStream(file))
}

android {
    signingConfigs {
        create("release") {
            keyAlias = keystoreProperties["keyAlias"] as String
            keyPassword = keystoreProperties["keyPassword"] as String
            storeFile = file(keystoreProperties["storeFile"] as String)
            storePassword = keystoreProperties["storePassword"] as String
        }
    }
    buildTypes {
        release {
            isMinifyEnabled = true
            isShrinkResources = true
            signingConfig = signingConfigs.getByName("release")
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
}

For Groovy DSL: same structure but use def keystoreProperties = new Properties(), untyped property access keystoreProperties['keyAlias'], minifyEnabled true (no is prefix), shrinkResources true, and signingConfig signingConfigs.release (no =).

Step 4 — ProGuard / R8 (Add Rules By Dependency)

R8 is NOT enabled by default in native Android — you must explicitly set isMinifyEnabled = true. Then add rules ONLY for libraries the project actually uses:

When R8 reports Missing class: — copy rules from the error output verbatim. When a crash occurs only in release build — the stripped class is in the stack trace.

Common rules (add only what applies):

# Kotlin (always needed with minification)
-keep class kotlin.Metadata { *; }
-dontwarn kotlin.**

# Coroutines
-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory {}
-keepnames class kotlinx.coroutines.CoroutineExceptionHandler {}
-keepclassmembers class kotlinx.coroutines.** { volatile <fields>; }

# kotlinx.serialization
-keepattributes *Annotation*, InnerClasses
-dontnote kotlinx.serialization.AnnotationsKt
-keepclassmembers class kotlinx.serialization.json.** { *** Companion; }
-keep,includedescriptorclasses class **$$serializer { *; }
-keepclassmembers class * { @kotlinx.serialization.Serializable *; }

# Retrofit + OkHttp
-keepattributes Signature, Exceptions
-keep class retrofit2.** { *; }
-keepclasseswithmembers class * { @retrofit2.http.* <methods>; }
-dontwarn okhttp3.**
-dontwarn okio.**

# Gson (consider migrating to kotlinx.serialization)
-keep class * extends com.google.gson.TypeAdapter
-keep class * implements com.google.gson.TypeAdapterFactory
-keepclassmembers,allowobfuscation class * {
    @com.google.gson.annotations.SerializedName <fields>;
}

Step 5 — Build Release AAB

./gradlew bundleRelease

Useful flags:

• --stacktrace — full stack trace on R8/signing errors.
• -Pandroid.injected.signing.store.file=... — override signing via CLI (CI use).
• ./gradlew clean bundleRelease — clean before building after Gradle config changes.

Output: app/build/outputs/bundle/release/app-release.aab

Step 6 — Verify Before Upload

# Verify signing — confirm alias is "upload", NOT "androiddebugkey"
keytool -printcert -jarfile app/build/outputs/bundle/release/app-release.aab

# Verify version (requires bundletool)
bundletool dump manifest --bundle=app/build/outputs/bundle/release/app-release.aab \
  | grep -E "versionCode|versionName"

Checklist:

• AAB signed with upload key (not debug) — debug key = #1 rejection reason
• versionCode higher than the previous upload
• keystore.properties and *.jks in .gitignore
• isMinifyEnabled = true and isShrinkResources = true both set
• ProGuard rules added only for reflection-heavy dependencies

NEVER Do

1. NEVER use the wrong minify property name — KTS: isMinifyEnabled. Groovy: minifyEnabled. The wrong one compiles fine but is a silent no-op — your release build is unminified, 3x larger, and exposes full source code. No error, no warning. Test by checking AAB size.

2. NEVER enable isShrinkResources without isMinifyEnabled — Resource shrinking depends on code minification to determine which resources are referenced. Without minify, shrink silently does nothing. Always set both.

3. NEVER set different store/key passwords with PKCS12 — keytool silently uses store password for key. Different passwords → signing fails with "Cannot recover key" (misleading — it's a password mismatch, not a corrupt key).

4. NEVER dump all ProGuard rules blindly — Add rules ONLY for libraries the project uses. Unnecessary -keep rules defeat the purpose of R8 by preventing dead code removal and increasing APK size.

5. NEVER skip testing the signed AAB — R8 stripping is invisible until runtime. Install the release build on a real device and test all screens, especially those using serialization, reflection, or native code. Crashes that only appear in release builds are always R8-related.

6. NEVER ignore lint errors by default — abortOnError = false in lint {} block is a common workaround, but it hides real issues. Fix lint errors first. Only suppress specific lint IDs you've reviewed: disable += "SomeSpecificCheck".

Common Errors

Gotchas

1. Java 17 is required for AGP 8+ — If build fails with "Unsupported class file major version", set org.gradle.java.home in gradle.properties to a JDK 17+ path. Or set JAVA_HOME in your shell environment.

2. local.properties must not be committed — Contains machine-specific SDK path. Always in .gitignore. If it's committed and another dev has a different SDK path, builds fail with confusing "SDK not found" errors.

3. App Signing by Google Play — Google re-signs your app with their app signing key. The keystore you generate is the upload key only. If you lose it, request a reset through Play Console (takes days, requires identity verification).

4. Flavor-aware build commands — With productFlavors, bundleRelease builds ALL flavors. To build a specific one: ./gradlew bundleProdRelease (capitalize flavor name). The output path also changes: app/build/outputs/bundle/prodRelease/.