# Troubleshooting > The failures this stack actually produces — permission-denied on a valid query, sessions that expire on relaunch, Metro resolution errors — and a Supabase to Firebase migration guide. **BNA UI** — a React Native / Expo component library. These components render through `react-native`, not the DOM: there are no HTML elements, no Tailwind classes and no Radix primitives. Source is copied into your project and imported through `@/components/ui/*`, `@/components/charts/*`, `@/hooks/*` and `@/theme/*`. Colours come from the `useColor` hook rather than hardcoded hex; sizing tokens (`HEIGHT`, `FONT_SIZE`, `BORDER_RADIUS`, `CORNERS`) come from `@/theme/globals`. - Docs: https://ui.ahmedbna.com/docs/firebase/troubleshooting - Markdown: https://ui.ahmedbna.com/docs/firebase/troubleshooting.md --- ## permission-denied on a query that looks fine The single most common one, and it is usually not a rules bug. **A read rule is evaluated against the query, not against the documents it would return.** Firestore refuses any query it cannot prove in advance is limited to documents the rule allows: ```ts // rule: allow read: if isOwner(resource.data.ownerId); query(collection(db, 'tasks'), orderBy('createdAt', 'desc')); // ❌ query(collection(db, 'tasks'), where('ownerId', '==', uid)); // ✅ ``` If you added a screen and it fails, check the query carries the same filter the rule keys on. See [Security rules](/docs/firebase/rules). The other cause: **the rules were never deployed.** A fresh project uses whatever the console last set. ```bash npm run deploy:rules ``` ## Everything is empty on a fresh scaffold Almost always one of two things: ```bash npx firebase-tools deploy --only firestore,storage # rules and indexes ``` or `.env.local` was never filled in. The client throws a readable error at import time when the config is missing, so check the Metro logs rather than the screen. ## "The query requires an index" Expected, and the error is doing you a favour — it carries a console URL that creates exactly the right index. `lib/errors.ts` passes that message through verbatim rather than replacing it with prose. Do not click through in production. Paste the generated definition into `firestore.indexes.json`, commit it, and: ```bash npm run deploy:indexes ``` A new index on an existing collection has to backfill, so queries keep failing until Firestore → Indexes shows it enabled. ## Users are signed out on every relaunch Persistence is not working. Either: - `lib/firebase.ts` threw its `getReactNativePersistence` error — check the logs. That is deliberate: the silent fallback is in-memory persistence, and failing loudly at startup beats a bug that reads as "sessions randomly expire". - Or you replaced `LargeSecureStore` with plain `expo-secure-store`. Firebase's user record exceeds its 2048-byte limit as soon as a Google identity with a long `photoURL` is attached — which is why it works with your test account and breaks for real users. ## createdAt.toMillis is not a function `serverTimestamp()` resolves to `null` in the local echo of a write — the snapshot delivered before the server acknowledges it. That is **every write**, not an edge case. Use the mapper in `lib/documents.ts`, or handle null in your own: ```ts createdAt: millisOf(doc.data().createdAt); // number | null ``` ## Metro cannot resolve firebase/auth If you hit this on Expo SDK 57, look for a `metro.config.js` you added. The `sourceExts.push('cjs')` and `unstable_enablePackageExports = true` advice in older Firebase + Expo threads describes defaults that `@expo/metro-config@57` and Metro 0.84 **already set**. Re-applying them by hand, particularly overwriting `unstable_conditionsByPlatform`, is now more likely to break resolution than fix it. Neither starter ships a `metro.config.js`. ## Firestore has already been started ``` FirebaseError: Firestore has already been started and its settings can no longer be changed ``` Something called `initializeFirestore` twice — usually a second module doing its own initialization, or a Fast Refresh re-run of an unguarded file. The starter derives everything from one `getApps()[0]` check: ```ts const existing = getApps()[0]; export const db = existing ? getFirestore(app) : initializeFirestore(app, settings); ``` Keep all initialization in `lib/firebase.ts`. ## Could not reach Cloud Firestore backend Usually a network path that blocks gRPC — a corporate proxy, some VPNs, or an awkward emulator setup. Swap the long-polling setting: ```ts initializeFirestore(app, { experimentalForceLongPolling: true }); ``` The two settings are **mutually exclusive** — remove `experimentalAutoDetectLongPolling` first or Firestore throws. ## Google sign-in does nothing | Symptom | Cause | | ------------------------------- | ----------------------------------------------------------------- | | Browser opens, redirect fails | Running in Expo Go. Needs a development build. | | `auth/invalid-credential` | ID token `aud` does not match `EXPO_PUBLIC_GOOGLE_WEB_CLIENT_ID`. | | No `id_token` in the result | Used `useAuthRequest` instead of `useIdTokenAuthRequest`. | | Works locally, fails in preview | Different signing key — add its SHA-1 as another Android client. | | Button does not appear | A client ID is unset. That is intended. | See [Google](/docs/firebase/google). ## Apple sign-in returns auth/invalid-credential The nonce is almost certainly swapped. Apple gets the **SHA-256 hash**; Firebase gets the **plaintext** as `rawNonce`. See [Apple](/docs/firebase/apple). ## The emulator will not start ``` firebase-tools no longer supports Java version before 21 ``` Install a JDK 21 or newer. The Firestore and Storage emulators are Java processes. ```bash java -version ``` ## Search finds nothing for a partial word Working as designed. Firestore has no `LIKE`, so search matches whole words against a `searchTokens` array — "migra" will not find "migration". If it finds nothing for a **whole** word, the tokens were not written: check that `add` calls `tokenize(text)`, and that any edit path rewrites `searchTokens` in the same `updateDoc`. ## Account deletion fails `auth/requires-recent-login`. Firebase refuses to delete an account on a token older than a few minutes. The confirm dialog asks a password user to type it; a federated user has to sign out and back in first. ## Data is left behind after deleting an account Expected, up to a point. Firestore has no `ON DELETE CASCADE`, so `useDeleteAccount` walks the data on the device — and a crash mid-way leaves orphans. For guarantees, use Firebase's "Delete User Data" extension or a Cloud Function on the `user.delete` trigger. Both need the Blaze plan, which is why neither ships here. ## Nothing is cached offline Firestore's `persistentLocalCache` is backed by IndexedDB, which React Native does not have. The cache is per-session memory only. This is the main limitation of the `firebase` JS SDK versus `@react-native-firebase`, and the most common reason to migrate later. --- # Moving from Supabase to Firebase The two starters build the same app, so most screens port with only import changes. These are the differences that matter. ## Authorization is inverted | | Supabase | Firebase | | ------------- | --------------------------- | ------------------------------- | | Where it runs | Postgres, per row | Google's servers, per **query** | | Unscoped read | Silently returns fewer rows | Fails with `permission-denied` | | The filter | Optional | **Mandatory** | This is the one that breaks ported code. A Supabase query relies on RLS to narrow the result; the Firebase equivalent must state the scope itself. ```ts // Supabase — RLS narrows this await supabase.from('tasks').select('*'); // Firebase — must be explicit or it fails outright query(collection(db, 'tasks'), where('ownerId', '==', uid)); ``` Note the Supabase starter's search screen deliberately _omits_ the user filter and says why; the Firebase one carries it and says the opposite. ## Schema and queries | Supabase | Firebase | | ------------------------------------ | -------------------------------------------------- | | SQL migrations | No schema — validate in `firestore.rules` | | `lib/database.types.ts` from codegen | Hand-written types in `lib/documents.ts` | | `is_complete`, `created_at` | `isComplete`, `createdAt` | | `ilike '%term%'` | `array-contains` over `searchTokens` — whole words | | Joins | Denormalise, or read twice | | `count()` | `getCountFromServer` | There is no `npm run db:types` equivalent because there is no schema to generate from. The CI job that checks generated types are current is replaced by one that executes the security rules. ## Realtime `onSnapshot` replaces the `postgres_changes` channel, and it does more: - No initial `select` — the listener delivers it. - No optimistic apply or rollback — the SDK handles both. - No refetch on reconnect — the stream resumes from a token. - **Errors are terminal.** A Supabase channel reconnects; a Firestore listener is torn down and needs an explicit retry. `lib/realtime.ts` has no counterpart and the starter ships none. See [Realtime](/docs/firebase/realtime). ## Auth | Supabase | Firebase | | ------------------------------------ | -------------------------------------------- | | `session` object | `User` with `getIdToken()` | | `AppState` refresh listener | Not needed | | Email OTP | **None** — SMS only | | GitHub via `signInWithOAuth` | **None** — needs a client secret | | Browser PKCE OAuth, works in Expo Go | Native ID token, needs a dev build | | `handle_new_user()` trigger | Client-side write from the snapshot listener | | `delete-account` edge function | Client-side `deleteUser`, best-effort | | Reset link returns to the app | Returns to a hosted page unless configured | `LargeSecureStore` carries over verbatim — Firebase's user record is over 2 KB for the same reason a Supabase session is. ## Functions Supabase edge functions have no free-tier equivalent: Cloud Functions require the Blaze plan. Before reaching for one, check whether the work can move to a security rule, a client-side call, or a Firebase extension — account deletion, for instance, needs no server at all here. ## Learn more - [Security rules](/docs/firebase/rules) — read this first - [Firestore](/docs/firebase/firestore) · [Authentication](/docs/firebase/auth) - [Report an issue](https://github.com/ahmedbna/ui/issues)