While building a React Native or Expo app with @react-native-firebase, you may encounter Metro bundler errors related to invalid package.json exports or a runtime crash saying a NativeModule does not exist. These errors usually appear after upgrading React Native, updating the Firebase SDK, installing a new Firebase module, switching from Expo Go to a development build, or updating Metro bundler. The root cause is almost always a conflict between the package.json `exports` field in Firebase packages and how Metro resolves modules.

The Error

1error: Package subpath './lib/module' is not defined by "exports"
2in node_modules/@react-native-firebase/app/package.json
3
4ERROR: NativeModule.RNFBAppModule does not exist in NativeModules
5
6Metro error: Unable to resolve module @react-native-firebase/auth
7from node_modules/@react-native-firebase/auth/lib/index.js:
8  Invalid package.json exports - package subpath not defined

You may also see variations like `Package path . is not exported from package`, `Cannot find module @react-native-firebase/app/lib/module/index`, or `NativeModule.RNFBAuthModule is null` at runtime even when the build succeeds.

What Causes This Error

The package.json `exports` field is a newer Node.js feature that controls which files inside a package can be imported and how they resolve. React Native Firebase added `exports` maps in recent versions to support ESM, but Metro bundler does not fully support the `exports` field in all configurations. When Metro encounters an `exports` map it cannot resolve, it throws an error instead of falling back to the `main` or `react-native` field.

• Metro bundler version does not fully support package.json exports field
• @react-native-firebase packages updated to a version with exports maps
• React Native or Expo upgraded but Metro config not updated
• Missing or outdated metro.config.js resolver settings
• Firebase native modules not linked (NativeModule does not exist at runtime)
• Using Expo Go instead of a development build with native Firebase modules
• Conflicting package versions between @react-native-firebase/app and other Firebase modules
• Yarn or npm hoisting placing Firebase packages in unexpected locations

Fix 1: Enable unstable_enablePackageExports in Metro Config

The most common fix is telling Metro to understand the `exports` field in package.json. Add the `unstable_enablePackageExports` flag to your metro.config.js resolver. This lets Metro resolve packages using their exports map instead of throwing an error.

1// metro.config.js
2const { getDefaultConfig, mergeConfig } = require('@react-native/metro-config');
3
4const defaultC getDefaultConfig(__dirname);
5
6const c {
7  resolver: {
8    unstable_enablePackageExports: true,
9  },
10};
11
12module.exports = mergeConfig(defaultConfig, config);

Expo Metro Config Version

1// metro.config.js
2const { getDefaultConfig } = require('expo/metro-config');
3
4const c getDefaultConfig(__dirname);
5
6config.resolver.unstable_enablePackageExports = true;
7
8module.exports = config;

After adding this flag, stop Metro completely, clear the cache, and restart.

1npx react-native start --reset-cache

Fix 2: Set unstable_conditionNames for React Native

Even with `unstable_enablePackageExports` enabled, Metro may pick the wrong export condition. Firebase packages export different entry points for `import`, `require`, `react-native`, and `default`. You need to tell Metro which conditions to use and in what priority order.

1// metro.config.js
2const { getDefaultConfig, mergeConfig } = require('@react-native/metro-config');
3
4const defaultC getDefaultConfig(__dirname);
5
6const c {
7  resolver: {
8    unstable_enablePackageExports: true,
9    unstable_conditionNames: [
10      'react-native',
11      'require',
12      'default',
13    ],
14  },
15};
16
17module.exports = mergeConfig(defaultConfig, config);

The order matters. Putting `react-native` first ensures Metro uses the React Native specific entry point when available. The `require` condition handles CommonJS imports, and `default` is the fallback.

Fix 3: Patch the Firebase Package.json Exports Field

If enabling exports support in Metro causes other packages to break, you can patch the specific Firebase package to remove or fix the exports field. Use patch-package to make the change survive npm install.

1npm install patch-package --save-dev

Open the Firebase package.json that is causing the error and either remove the `exports` field entirely or fix the subpath that Metro cannot resolve.

1// node_modules/@react-native-firebase/app/package.json
2// Find the "exports" field and remove it:
3
4// BEFORE
5{
6  "name": "@react-native-firebase/app",
7  "main": "lib/index.js",
8  "exports": {
9    ".": {
10      "import": "./lib/module/index.js",
11      "require": "./lib/index.js"
12    }
13  }
14}
15
16// AFTER (remove exports so Metro uses "main" field)
17{
18  "name": "@react-native-firebase/app",
19  "main": "lib/index.js"
20}

After editing, create the patch and add the postinstall script.

1npx patch-package @react-native-firebase/app

1// package.json
2{
3  "scripts": {
4    "postinstall": "patch-package"
5  }
6}

Fix 4: Align All Firebase Package Versions

React Native Firebase requires all @react-native-firebase packages to be on the same version. If @react-native-firebase/app is v21.x but @react-native-firebase/auth is v20.x, you will get module resolution errors, missing exports, or NativeModule crashes.

1# Check all Firebase package versions
2npm ls @react-native-firebase/app
3npm ls @react-native-firebase/auth
4npm ls @react-native-firebase/firestore
5npm ls @react-native-firebase/messaging
6npm ls @react-native-firebase/storage
7
8# Update all Firebase packages to the same version
9npm install @react-native-firebase/app@latest \
10  @react-native-firebase/auth@latest \
11  @react-native-firebase/firestore@latest \
12  @react-native-firebase/messaging@latest \
13  @react-native-firebase/storage@latest
14
15# For Expo: use expo install to get compatible versions
16npx expo install @react-native-firebase/app \
17  @react-native-firebase/auth \
18  @react-native-firebase/firestore

Fix 5: NativeModule Does Not Exist (Runtime Crash)

If the Metro build succeeds but the app crashes at runtime with `NativeModule.RNFBAppModule does not exist in NativeModules` or similar Firebase NativeModule errors, the native Firebase modules are not linked to your app. This is a separate issue from the exports error.

• If using Expo Go: Firebase requires native code, you must switch to a development build with expo-dev-client
• If using bare React Native: run pod install on iOS and rebuild, Firebase auto-links but needs a native rebuild
• If using Expo prebuild: run npx expo prebuild --clean to regenerate native projects with Firebase native modules
• Check that GoogleService-Info.plist (iOS) and google-services.json (Android) are in the correct locations
• Make sure @react-native-firebase/app is imported before any other Firebase module

1// App.tsx or index.js - import app FIRST
2import '@react-native-firebase/app';
3import auth from '@react-native-firebase/auth';
4import firestore from '@react-native-firebase/firestore';

Expo Development Build Setup

1# Install expo-dev-client if not already installed
2npx expo install expo-dev-client
3
4# Regenerate native projects with Firebase
5npx expo prebuild --clean
6
7# Build and run
8npx expo run:ios
9npx expo run:android

Fix 6: Update Metro Bundler

Older Metro versions have worse support for the package.json exports field. If you are on Metro 0.76 or older, updating to Metro 0.80 or above significantly improves exports resolution. Check your Metro version and upgrade if needed.

1# Check Metro version
2npx metro --version
3
4# Or check in node_modules
5cat node_modules/metro/package.json | grep version
6
7# For bare React Native: Metro is tied to your RN version
8# Upgrading React Native upgrades Metro
9
10# For Expo: Metro version is tied to Expo SDK
11# Upgrade Expo SDK to get the latest Metro
12npx expo install expo@latest
13npx expo install --fix

Fix 7: Clear All Caches and Rebuild

After making any of the above changes, you must clear all caches. Metro aggressively caches module resolutions, so even after fixing metro.config.js, the old broken resolution may be cached.

1watchman watch-del-all
2
3rm -rf node_modules
4npm install
5
6rm -rf $TMPDIR/metro-*
7rm -rf $TMPDIR/haste-map-*
8
9cd ios
10rm -rf Pods Podfile.lock build
11pod install --repo-update
12cd ..
13
14cd android
15./gradlew clean
16cd ..
17
18npx react-native start --reset-cache

Expo Full Rebuild

1watchman watch-del-all
2
3rm -rf node_modules ios android .expo
4npm install
5
6npx expo prebuild --clean
7npx expo run:ios
8npx expo run:android

Quick Diagnosis Checklist

• Check if metro.config.js has unstable_enablePackageExports set to true
• Check if unstable_conditionNames includes react-native, require, and default
• Run npm ls @react-native-firebase/app and check all Firebase packages are on the same version
• Check Metro version with npx metro --version
• If NativeModule error at runtime: are you using Expo Go instead of a development build?
• Is @react-native-firebase/app imported before all other Firebase modules?
• Are GoogleService-Info.plist and google-services.json in the correct locations?
• Did you run pod install on iOS after installing Firebase packages?
• Clear Metro cache with --reset-cache after any config change
• If patch-package is used: check that patches are applied after npm install

Final Working Metro Config

1// metro.config.js (bare React Native)
2const { getDefaultConfig, mergeConfig } = require('@react-native/metro-config');
3
4const defaultC getDefaultConfig(__dirname);
5
6const c {
7  resolver: {
8    unstable_enablePackageExports: true,
9    unstable_conditionNames: [
10      'react-native',
11      'require',
12      'default',
13    ],
14  },
15};
16
17module.exports = mergeConfig(defaultConfig, config);

1// metro.config.js (Expo)
2const { getDefaultConfig } = require('expo/metro-config');
3
4const c getDefaultConfig(__dirname);
5
6config.resolver.unstable_enablePackageExports = true;
7config.resolver.unstable_c [
8  'react-native',
9  'require',
10  'default',
11];
12
13module.exports = config;

Official-Style Error Explanation

The React Native Firebase invalid package.json exports error occurs when Metro bundler cannot resolve module paths through the `exports` field in @react-native-firebase package.json files. Metro historically used the `main` and `react-native` fields for module resolution, but newer Firebase versions added `exports` maps for ESM compatibility. When Metro encounters an exports map it does not support or cannot resolve, the build fails with `Package subpath is not defined by exports` or `Invalid package.json exports`. The fix is to enable `unstable_enablePackageExports` and set `unstable_conditionNames` in metro.config.js so Metro resolves Firebase modules through the exports field correctly. The separate runtime error where NativeModule does not exist happens when Firebase native code is not compiled into the app binary, usually because the project uses Expo Go instead of a development build, or because pod install was not run after installing Firebase packages.