Android: protobuf-java conflicts with Firebase (protobuf-javalite) causing DuplicateClass and VerifyError

[muhammedjasircp]

Description

When using mobile-payments-sdk-react-native alongside Firebase (Firestore/Auth/Crashlytics) on Android, the build fails with DuplicateClass errors and/or the app crashes at runtime with VerifyError.

The root cause is a dependency conflict between the two SDKs:

• Square Mobile Payments SDK (all versions 2.3.0–2.5.0) depends on com.google.protobuf:protobuf-java (full runtime)
• Firebase Android SDKs depend on com.google.protobuf:protobuf-javalite (lite runtime)

These two protobuf variants have incompatible class hierarchies. For example, com.google.protobuf.Timestamp extends GeneratedMessage in protobuf-java but extends GeneratedMessageLite in protobuf-javalite. Firebase's compiled bytecode contains casts like (GeneratedMessageLite) Timestamp, which fail at runtime with VerifyError when protobuf-java is on the classpath.

There is no Gradle exclusion workaround that resolves this:

• Excluding protobuf-java fixes the dex DuplicateClass build error, but Square SDK may fail if it relies on full-protobuf APIs at runtime.
• Excluding protobuf-javalite causes a new DuplicateClass (from protolite-well-known-types) and then VerifyError at runtime because Firebase's bytecode was compiled against GeneratedMessageLite, not GeneratedMessage.

Steps to reproduce

1. Create a React Native project using mobile-payments-sdk-react-native
2. Add Firebase to Android: @react-native-firebase/app, @react-native-firebase/firestore, @react-native-firebase/auth, @react-native-firebase/crashlytics
3. Run ./gradlew assembleDebug

Expected behavior

Build succeeds and app runs without crash. Both Square SDK and Firebase coexist on Android.

Actual behavior

Build-time error (DuplicateClass):

DuplicateClass com.google.protobuf.AbstractMessageLite found in modules
  protobuf-java-3.25.3.jar (com.google.protobuf:protobuf-java:3.25.3)
  protobuf-javalite-3.25.1.jar (com.google.protobuf:protobuf-javalite:3.25.1)

Runtime error if protobuf-java is excluded (VerifyError):

java.lang.VerifyError: Verifier rejected class com.google.firebase.firestore.proto.WriteResponse
  because: com.google.protobuf.Timestamp is not instance of
  com.google.protobuf.GeneratedMessageLite (declaration of
  'com.google.firestore.v1.WriteResponse' appears in
  /data/app/.../base.apk)

Environment

• mobile-payments-sdk-react-native: 2025.12.1 (native SDK 2.3.1–2.5.0, all affected)
• @react-native-firebase/app: 21.x
• React Native: 0.79.x
• Android: minSdk 28, compileSdk 35

Workaround

Exclude the Square SDK from Android autolinking (react-native.config.js) and provide a no-op JS stub for Android via platform-specific files (.android.ts). This means Square card payments are unavailable on Android.

Request

Please consider migrating the native Android SDK's protobuf dependency from protobuf-java to protobuf-javalite. Firebase and most modern Android libraries use javalite, and it is Google's recommended protobuf variant for Android. This would allow Square SDK and Firebase to coexist without conflicts.

[Armaxis]

Hey @muhammedjasircp, thanks for the detailed writeup. Unfortunately, this is a known limitation.

Root cause: the native Android SDK pulls in the full com.google.protobuf:protobuf-java runtime via retrofit2:converter-protobuf, while Firebase depends on protobuf-javalite. The two ship the same com.google.protobuf.* classes with incompatible hierarchies, so they can't share a classpath - the upstream limitation in protocolbuffers/protobuf#8104. As you found, no exclude/resolutionStrategy combination leaves both SDKs working: dropping javalite crashes Firebase with VerifyError, dropping protobuf-java breaks our SDK. We've seen the same conflict on the Flutter wrapper (flutter#13).

On migrating to javalite: agreed it's the better fit for Android, but being honest about feasibility - our native SDK is built from a large shared monorepo where generated protobuf classes are committed as compiled protobuf-java sources shared with other Square products, so it's a cross-cutting migration rather than a dependency swap. We'd like to do it eventually, but it's not near-term.

What's promising on our side: shading/relocating our protobuf runtime inside the SDK so it stops colliding with Firebase's copy - much smaller than a full migration. We're evaluating it; no timing commitment yet.

For now: keeping the Square SDK off Android autolinking and stubbing it there (what you're already doing) is the most reliable option if you can't drop either dependency. You can also experiment with exclusion rules, but it's not guaranteed to work in the end.

[muhammedjasircp]

Confirmed runtime crash details

After further investigation with native bytecode analysis and a live Android device test, here is the exact crash trace:

E AndroidRuntime: FATAL EXCEPTION: main
E AndroidRuntime: Caused by: java.lang.ClassNotFoundException: com.squareup.lando.service.challenge.Challenge$ChallengeRequest
E AndroidRuntime: Caused by: java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/protobuf/GeneratedMessageV3;
E AndroidRuntime:   at com.squareup.sdk.mobilepayments.MobilePaymentsSdk.initialize(MobilePaymentsSdk.kt:23)
E AndroidRuntime:   at com.django.MainApplication.onCreate(MainApplication.kt:42)

com.squareup.lando.service.challenge.Challenge$ChallengeRequest (in a transitive AAR dependency of mobile-payments-sdk) extends com.google.protobuf.GeneratedMessageV3 from protobuf-java. This class is loaded during Dagger injection inside MobilePaymentsSdk.initialize() → BootstrapHelper → DaggerMobilePaymentsSdkComponent.

With protobuf-java excluded (required to avoid DuplicateClass against Firebase's protobuf-javalite), this class cannot be resolved and the app crashes immediately on startup.

This confirms the conflict is not just in the POM dependency declaration — it is a hard runtime requirement. GeneratedMessageV3 must be on the classpath for the SDK to initialize.

The only viable path for apps using both Firebase and Square SDK on Android is dependency shading: relocate com.google.protobuf → a private namespace in all Square/lando transitive AARs and the protobuf-java runtime, so Firebase's canonical com.google.protobuf namespace (javalite) is unaffected.

Migrating the native Android SDK's generated classes from protobuf-java to protobuf-javalite (or to Wire, which Square already uses extensively) would permanently resolve this.

[muhammedjasircp]

Update: protobuf shading works as a full workaround. Confirmed Square SDK and Firebase now coexist on Android with no DuplicateClass, VerifyError, or the ClassNotFoundException/NoClassDefFoundError at MobilePaymentsSdk.initialize() I posted above.

Approach:

• Used the Gradle Shadow plugin to relocate com.google.protobuf → a private namespace (com.squareup.shaded.protobuf) inside mobile-payments-sdk-internals + protobuf-java:3.25.3 + retrofit2:converter-protobuf (shaded together since converter-protobuf references protobuf-java directly)
• Published the shaded jar to a local Maven repo, declared ahead of Square's own Maven repo in repositories {}
• Globally excluded the original com.google.protobuf:protobuf-java and com.squareup.retrofit2:converter-protobuf from the dependency graph, so Firebase's protobuf-javalite remains the only unshaded com.google.protobuf.* on the classpath
• Verified by decompiling the actual dexed build output — confirmed zero references to unshaded com.google.protobuf.*, and Challenge$ChallengeRequest (the exact class from my crash trace above) correctly relocated to the shaded namespace

This fully resolves the Dagger-injection crash — GeneratedMessageV3 now resolves fine since it lives inside the SDK's own shaded jar instead of depending on an external protobuf-java that collides with Firebase's protobuf-javalite.

Happy to share the Gradle scripts (ShadowJar task config + local-maven publish/update script) if it'd help others hitting this — it's a ~15 min one-time setup, repeatable on each SDK version bump via a small wrapper script, no monorepo migration needed on your end. This got us fully unblocked shipping Square + Firebase together on Android.