Firebase Crashlytics (Expo / React Native)

Minimum viable example

import crashlytics from "@react-native-firebase/crashlytics";

// Set context once the user signs in
crashlytics().setUserId(user.uid);

// In your error boundary
componentDidCatch(error: Error) {
  crashlytics().recordError(error);
}

Native crashes are captured automatically once the plugin is installed. JS errors require recordError — they don't surface otherwise.

1. Install

npx expo install @react-native-firebase/crashlytics

app.json:

{
  "expo": {
    "plugins": [
      "@react-native-firebase/app",
      "@react-native-firebase/crashlytics"
    ]
  }
}

Rebuild — Crashlytics requires native linking:

npx expo prebuild --clean
eas build --profile development --platform all

2. Verify it works

The most reliable way to confirm Crashlytics is wired is to force a crash and check the console:

import crashlytics from "@react-native-firebase/crashlytics";

// Tied to a debug-only button:
function ForceCrashButton() {
  return <Button title="Crash" onPress={() => crashlytics().crash()} />;
}

After tapping:

1. The app dies (this is expected)
2. Relaunch the app — Crashlytics uploads the report on next start
3. Wait 5-15 minutes, then check Firebase Console → Crashlytics

If nothing appears after 30 minutes, see references/troubleshooting.md.

3. JavaScript errors

Native crashes are captured automatically. JS errors are not — wrap your error boundary and unhandled-rejection handlers:

import crashlytics from "@react-native-firebase/crashlytics";

// Unhandled promise rejections
const origHandler = global.HermesInternal?.hasPromise?.()
  ? require("promise/setimmediate/rejection-tracking")
  : null;
// Or use react-native-exception-handler / your error boundary

// In your error boundary's componentDidCatch:
componentDidCatch(error: Error, info: React.ErrorInfo) {
  crashlytics().recordError(error, error.name);
}

recordError reports a non-fatal — visible in Crashlytics under a separate tab. The app keeps running.

4. Context: user IDs and custom keys

Add context so you can debug a specific user's crashes:

import auth from "@react-native-firebase/auth";

auth().onAuthStateChanged((user) => {
  if (user) {
    crashlytics().setUserId(user.uid);
    crashlytics().setAttributes({
      email: user.email ?? "",
      tier: "pro",
    });
  } else {
    crashlytics().setUserId("");
  }
});

setUserId is searchable in the console — typing the uid jumps straight to that user's reports.

5. Breadcrumbs (custom logs)

Log a trail of recent actions so you can see what led to the crash:

crashlytics().log("User tapped Pay button");
crashlytics().log(`Order ${orderId} submitted`);

These appear in the crash report under "Logs". Keep them short — they have a per-report quota.

6. Source maps (so JS stacks are readable)

Without source maps, JS errors show minified stacks. To upload maps on every EAS build, add a post-build hook in eas.json:

{
  "build": {
    "production": {
      "ios":     { "buildConfiguration": "Release" },
      "android": { "buildType": "app-bundle" }
    }
  }
}

Then run the upload step locally after eas build finishes (the build artifacts include the sourcemap). The exact command depends on @react-native-firebase version — newer versions auto-upload via the bundle phase script when Crashlytics is in the plugin list.

For native iOS dSYMs (required for symbolicated native crashes): EAS Build uploads dSYMs to App Store Connect automatically; you must download them and upload to Crashlytics if you're not using auto-upload. Enable automatic dSYM upload in the Firebase console: Project Settings → iOS app → "Upload symbols".

7. Common mistakes

• Expecting JS errors to appear automatically. They don't — only native crashes. You must call recordError from your error boundary.
• Forgetting to relaunch after a crash. Crashlytics uploads on the next app start, not from the crashed process.
• Testing in debug. Some configs disable Crashlytics in debug builds. Force a crash in a release / preview build to verify.
• Reading minified stacks. If you see at l (index.android.bundle:1:12345), source maps are not wired.
• Setting user ID before sign-in completes. Wait for onAuthStateChanged to fire with a user before calling setUserId.