Version 27 bundles several breaking behavior corrections and dependency bumps that landed after v26:

• Firebase JS SDK 12.18.0 — on web/macOS (Platform.other), FunctionsError.message appends an HTTP status suffix and customData.url is populated (#9218).
• Cloud Messaging — four documented runtime contracts are enforced after previous accidental shapes (#9246, #9247, #9252, #9254).
• Imagen API removed from @react-native-firebase/ai after Google shut down the Imagen models as a service on 2026-08-17. Generate images with a Gemini image model through getGenerativeModel() instead.

If you are upgrading from v25 or earlier, complete Migrating to v26 first — the namespaced API removal and New Architecture requirement still apply.

• Agent-assisted migration
• Firebase JS SDK 12.18.0
• Cloud Messaging
  • String APNs sound → notification.ios.sound
  • iOS sentTime is epoch milliseconds
  • iOS badge is a string
  • onMessageSent receives a string message ID
• Removed Imagen API
  • Example
• Automated migration checklist

This guide is written to be complete enough for an automated first pass. We recommend feeding this document to your coding agent, then asking it to analyze your codebase against each relevant section below and produce a concrete change list (or PR) for the packages you use. The Automated migration checklist at the end is structured for that workflow.

PR: #9218

React Native Firebase pins firebase-js-sdk 12.18.0. On web and macOS (Platform.other), Cloud Functions uses the JS SDK callable path. That path now enriches FunctionsError (aliased as HttpsError in React Native Firebase):

Native iOS and Android continue to surface callable failures through the native bridge as HttpsError without the HTTP status suffix. Do not assume the suffix or customData.url on those platforms.

1. Search for exact-equality checks on error.message / e.message for callable failures.
2. On web/macOS, prefer message.startsWith(expected) or strip a trailing [digits] before comparing.
3. If you need the HTTP status or request URL, read them from the suffix / customData.url on web/macOS only; keep a native fallback path for iOS/Android.

// Previously (exact match — breaks on web/macOS after 12.18.0)
if (e.message === 'Invalid test requested.') {
  /* … */
}

// Now (tolerant of the optional " [status]" suffix)
const base = e.message.replace(/ \[\d+\]$/, '');
if (base === 'Invalid test requested.') {
  /* … */
}
// Optional on Platform.other:
// e.customData?.url

Upstream note: firebase@12.18.0 — “Add HTTP status code to the message field and add url to customData.”

These changes correct runtime behavior to match the public RemoteMessage / listener contracts. There is no new public TypeScript surface — consumers that worked around the old accidental shapes must update.

PR: #9246

String-valued APNs sounds are serialized at the documented message.notification.ios.sound path. Previously, only string sounds were placed at the undocumented message.notification.sound path (critical-sound dictionaries already used the correct iOS nesting).

// Previously
const sound = message.notification?.sound;

// Now
const sound = message.notification?.ios?.sound;

PR: #9247

On iOS, RemoteMessage.sentTime is a number of epoch milliseconds, matching Android and the public type. FCM supplies seconds (often as a string); native serialization converts those values to milliseconds.

Android behavior is unchanged. Remove parseInt / string comparisons that assumed seconds.

// Previously (iOS)
const sentMs = Number(message.sentTime) * 1000;

// Now (iOS and Android)
const sentMs = message.sentTime; // number, epoch ms

PR: #9252

iOS aps.badge is serialized as a string, matching RemoteMessage.notification.ios.badge?: string.

// Previously
const badge = message.notification?.ios?.badge; // number on iOS

// Now
const badge = Number(message.notification?.ios?.badge ?? 0);

PR: #9254

onMessageSent listeners receive the documented message-ID string. Android previously forwarded the transport wrapper { messageId } to application code.

// Previously
onMessageSent(messaging, ({ messageId }) => {
  console.log(messageId);
});

// Now
onMessageSent(messaging, messageId => {
  console.log(messageId);
});

Nothing else in @react-native-firebase/ai changed. getGenerativeModel(), getTemplateGenerativeModel(), TemplateGenerativeModel, and Gemini image generation are unaffected.

{/* prettier-ignore */}

// Previously (removed)
import { getApp } from '@react-native-firebase/app';
import { getAI, getImagenModel, ImagenAspectRatio } from '@react-native-firebase/ai';

const ai = getAI(getApp());
const imagenModel = getImagenModel(ai, {
  model: 'imagen-3.0-generate-002',
  generationConfig: {
    aspectRatio: ImagenAspectRatio.LANDSCAPE_16x9,
  },
});

const result = await imagenModel.generateImages('Draw a red bicycle on a beach at sunset');
console.log(result.images[0].mimeType);

// Now
import { getApp } from '@react-native-firebase/app';
import {
  getAI,
  getGenerativeModel,
  ImageConfigAspectRatio,
  ImageConfigImageSize,
  ResponseModality,
} from '@react-native-firebase/ai';

const ai = getAI(getApp());
const model = getGenerativeModel(ai, {
  model: 'gemini-3.1-flash-image',
  generationConfig: {
    responseModalities: [ResponseModality.IMAGE],
    imageConfig: {
      aspectRatio: ImageConfigAspectRatio.LANDSCAPE_16x9,
      imageSize: ImageConfigImageSize.SIZE_1K,
    },
  },
});

const result = await model.generateContent('Draw a red bicycle on a beach at sunset');
const imagePart = result.response.inlineDataParts()?.[0];
console.log(imagePart?.inlineData.mimeType);

See AI Logic usage for more image generation examples, and Google's Imagen to Gemini migration guide for model and prompt guidance.

Use this section when running scripted or agent-assisted upgrades from v26 → v27.

# Bump all @react-native-firebase/* packages to v27 together (monorepo versions are aligned)
yarn add @react-native-firebase/app@^27.0.0 …
cd ios && pod install

Confirm the lockfiles resolve firebase / firebase-js-sdk 12.18.0+.

For each area you use, search the listed symbols and apply the replacements:

yarn compile
# TypeScript consumers: fix compile errors from removed Imagen exports and messaging types
# Manually exercise: callable error message handling (web/macOS), FCM notification fields (iOS), onMessageSent, Gemini image generation