Firebase JavaScript SDK Release Notes

To review release notes for the Firebase console and for other Firebase platforms and related SDKs, refer to the Firebase Release Notes.

Version 12.19.0 - September 9, 2026

Fixed an issue where the SDK hardcoded an invalid function role, causing 400 errors during function calling on newer Gemini models like gemini-3.6-flash.
Fixed client-side validation logic that incorrectly blocked text/x.enum when responseSchema or responseJsonSchema was provided. The SDK now correctly accepts both application/json and text/x.enum for structured outputs.

Allowed IndexedDB persistence reconnection on demand after pagehide events, fixing "Database is closing" errors during signInWithPopup authentication on iPadOS and iOS Safari. See GitHub issue #10318.
Added a graceful fallback to in-memory persistence when persistence initialization fails or storage is inaccessible, preventing initialization deadlocks and ensuring authStateReady() resolves. See GitHub issue #10311.
Wrapped storage and persistence errors in FirebaseError (auth/internal-error) during current user updates, ensuring error.code is always defined and attaching the underlying exception under error.customData.originalError.

Added support for conversion and serialization between Temporal.Instant and Firestore's Timestamp.
Fixed an issue where fetch connection error messages were displayed as undefined.

Updated a number of top-level devDependencies, including some that may affect the build bundle.

Imagen methods and types have been removed due to Imagen models being shut down. As a replacement, you can migrate your apps to use Gemini Image models (the "Nano Banana" models).
Fixed incorrect detection of LanguageModel that prevented usage of on-device models in Chrome Extensions.

Added more details to FunctionsError. Added HTTP status code to the message field and add url to customData.

Updated debug token log message to include Firebase CLI commands, Firebase Console registration link, and debug token guide.

Fixed an issue where signInWithPopup and other background tab operations failed with the error "Database is closing/hidden". See GitHub issue #10264.

Updated the WebSocket URL path for SQL Connect server affinity, to improve server resource usage efficiency and performance.
Fixed an issue preventing App Check tokens from being properly recognized when sent in Firebase SQL Connect Realtime requests.