expo-iap ships no consumer ProGuard rules — subscription replacement fails silently in release builds

[acpmarcodev]

Summary

expo-iap does not ship any consumer ProGuard/R8 rules, and its android/build.gradle does not declare consumerProguardFiles. In a release build with R8 enabled (the Expo default), the subscription replacement flow fails at runtime with the system message "This feature is not supported on this device" — no build error, no exception, and it does not reproduce in debug.

Adding a -keep for the Billing API in the app's ProGuard file fixes it. Since this affects every consumer that ships a minified release with subscription replacement, the rule arguably belongs in the library.

Environment

expo-iap	5.0.1 (first hit) and 5.2.2 (still reproduces)
openiap-google	3.0.1 → 3.2.2
Google Play Billing	9.1.0
Expo SDK	57
React Native	0.86
Kotlin	2.2.0
Build	Android release AAB, minifyEnabled true

What happens

Calling requestPurchase with subscriptionProductReplacementParams (upgrade with charge-full-price, downgrade with deferred):

• debug build → replacement flow works, purchase sheet opens
• release build (R8) → the store returns "This feature is not supported on this device" before any payment sheet; no crash, no build warning

Steps to reproduce

1. Expo SDK 57 app with expo-iap, subscriptions configured with a monthly base plan
2. Build a release artifact with minifyEnabled true (Expo default for release)
3. With an active subscription, trigger a tier change via requestPurchase({ ..., subscriptionProductReplacementParams: { oldProductId, replacementMode } })
4. Observe the failure above; the same code path works in debug

Workaround

This is what we currently carry in the consuming app's android/app/proguard-rules.pro:

# expo-iap/openiap-google calls newer Google Play Billing APIs through
# reflection. Keep Billing API names in release builds so R8 does not rename
# methods such as setSubscriptionProductReplacementParams.
-keep class com.android.billingclient.api.** { *; }

After that, replacement (both charge-full-price and deferred) works in release.

Suggested fix

Ship the keep rule with the library, so consumers get it automatically:

• add a consumer-rules.pro under android/ containing the Billing keep, and
• reference it via consumerProguardFiles 'consumer-rules.pro' in android/build.gradle

Note on the cause

I did not read the openiap-google source, so I can't confirm the mechanism — the comment in the snippet above is our own working hypothesis. The symptom is consistent with the Billing APIs being reached reflectively (R8 renames what it cannot see referenced statically), which would explain why only release builds break and why a -keep on the Billing package resolves it. If the access is in fact static, the root cause may be different — but the missing consumer rule and the reproducible release-only failure stand either way.

Happy to test a patch release against the same setup.

[hyochan]

Confirmed that the failing path was not an Expo-only consumer-rule handoff problem. openiap-google already publishes its consumer rules through the AAR, but subscription product replacement was assembled through class- and method-name reflection. R8 could optimize those Billing symbols in minified release builds, making the reflective path unreliable even though the AAB built successfully.

The fix replaces that reflection with typed Play Billing 9.1 API calls, adds direct native-builder coverage for every replacement mode, and verifies a minified Play release without a broad Billing package keep rule. Play, Horizon, and Amazon compilation and release assembly also pass. A final store-backed replacement purchase still requires an active Google Play Sandbox subscription and reporter validation.

Fix is up in #309.

Note: This repository (OpenIAP monorepo) handles development for all framework libraries from the versions listed below. For earlier versions, refer to the archived individual repositories.

• react-native-iap v15.0.0+
• expo-iap v4.0.0+
• flutter_inapp_purchase v9.0.0+
• godot-iap v2.0.0+
• kmp-iap v2.0.0+