FlutterFlow Not Working? Fix the 10 Most Common Errors (2026)

Start Here: 2-Minute FlutterFlow Triage

Before changing widgets, rules, or backend settings, reproduce the bug where users see it. Open the deployed web app or installed build in an incognito browser or clean test device. Open DevTools, then check Console, Network filtered to Fetch/XHR, and Application storage. For mobile builds, use the Debug Info panel in Test Mode, and Project Issues in the toolbar, Firebase console logs, Supabase logs, or local Flutter logs if you exported the code.

Console errors usually tell you whether the failure is frontend, backend, or build related. A red CORS, 401, 403, 404, or 500 message points to an API or permission issue. A silent spinner with no network traffic often means startup state, app initialization, or navigation logic is blocking the first page. A release-only auth failure usually means signing keys, bundle IDs, package names, redirect domains, or Firebase app registration do not match the shipped binary.

Network tells you what the app actually sent. If the request has the wrong base URL, missing authorization header, wrong content type, or an unexpected empty parameter, fix FlutterFlow's API Call definition before blaming the backend. If the request is correct but the backend rejects it, inspect rules, policies, secrets, or server logs.

For teams using FlutterFlow as the primary builder, the biggest trap is treating every issue as a visual editor problem. Many failures are configuration drift between FlutterFlow, Firebase, Supabase, Apple, Google, and exported Flutter tooling.

1. App Stuck on the Splash or Loading Screen After Publishing

What it looks like: the app opens, shows the FlutterFlow splash screen or your first loading widget, then never reaches the home page. Preview may work, but the deployed web app or installed build hangs. Users describe it as FlutterFlow is not working because there is no visible error.

Why it happens: most often, the initial page waits for app state, Firebase initialization, a user document query, or a remote config value that never resolves. The second most common cause is a startup action that redirects in a loop. Another common cause is an environment-only failure, such as a missing production API URL or storage permission.

Fix the splash screen hang:

1. Open the released app with DevTools and check Console for initialization errors such as FirebaseError, permission-denied, or missing asset messages.
2. In FlutterFlow, open Settings and Integrations: Firebase lives under Project Setup > Firebase, Supabase under Integrations > Supabase, and environments under App Settings > Dev Environments (Growth plan and above). Confirm all three point at the backend the release build should use for the target release build.
3. Inspect the first page's On Page Load actions. Temporarily disable redirects, backend queries, and blocking custom actions until the page renders.
4. Check every conditional navigation rule that depends on currentUser, currentUserDocument, or app state. Add a fallback path for null or timeout cases.
5. If the app uses Firebase user documents, confirm the document is created during signup before the home page queries it.
6. Deploy a minimal release with only the splash and home page. Add startup dependencies back one at a time.

"Review this FlutterFlow startup flow. The app hangs on splash after publishing. Identify any blocking page-load action, auth-state dependency, or navigation loop. Error/logs: [paste error]."

A useful comparison is whether the failure happens before or after the first network request.

When to call an expert: bring in help when the app has multiple startup redirects, auth checks, and backend reads chained together, because guessing can create a login loop that only appears in production.

2. Firebase Authentication Failing Only on the Released Build

What it looks like: email, Google, Apple, or phone login works in FlutterFlow preview, but the TestFlight, Play Store, APK, or published web build rejects login. You may see auth/invalid-api-key, auth/unauthorized-domain, ApiException: 10, or a redirect back to login.

Why it happens: most often, the released app is not the same Firebase app that preview used. Android SHA-1 or SHA-256 fingerprints are missing, iOS bundle IDs do not match, web domains are not authorized, or OAuth redirect settings were configured for preview only. Phone auth adds another layer because device verification depends on app signing and platform setup.

Fix released Firebase auth:

1. In Firebase, open Project settings and confirm the Android package name and iOS bundle ID match FlutterFlow's release settings exactly.
2. For Android, add SHA-1 and SHA-256 for the debug key, upload key, and Play App Signing key where applicable.
3. For web, open Authentication, then Settings, and add the deployed domain to Authorized domains.
4. Download fresh google-services.json and GoogleService-Info.plist if identifiers changed, then reconnect Firebase in FlutterFlow.
5. Check every login action for a destination page that assumes the user document already exists.
6. Run one clean release build after clearing old app data on the test device.

"Diagnose this FlutterFlow Firebase auth failure in a released build. Compare preview versus release config, signing keys, bundle IDs, authorized domains, and post-login navigation. Error: [paste error]."

The full auth-specific walkthrough is in our guide to fixing FlutterFlow Firebase auth errors fast. If your project also uses Firestore user documents, read the rules section below before changing signup logic.

When to call an expert: call an expert when auth works for one provider but not another, or when the build is already live and changing Firebase identifiers could lock out existing users.

3. Firestore Security Rules Blocking Reads

What it looks like: pages that should show records are blank, loading indicators spin, or the console shows FirebaseError: Missing or insufficient permissions. The document exists in Firebase, but FlutterFlow cannot read it as the signed-in user.

Why it happens: most often, Firestore rules require ownership fields that your documents do not actually contain. The second most common cause is a query that filters by one field while the rule checks another. A third cause is preview mode using a different auth state than the released app.

Fix Firestore rule failures:

1. Confirm the denial in the Console, not the Network tab: the Firestore SDK reports permission-denied inside the response stream, so the network request itself usually returns 200. On a mobile build there is no browser Network tab at all, so read it from the run output.
2. Before touching the Firebase console, open Firestore in FlutterFlow and look at the rules FlutterFlow generates for that collection: FlutterFlow deploys its own ruleset over Firebase, so a rule you hand-write in the console is overwritten the next time you press Deploy. If you need a custom rule, tick Exclude on that collection in FlutterFlow first. Then, in Firebase, open Firestore Database, then Rules, and find the collection used by the failed FlutterFlow backend query.
3. Compare the rule's required fields, such as ownerId, uid, created_by, or document path IDs, against real documents.
4. In FlutterFlow, open the page's backend query and verify the collection, filters, and query type match the intended rule path.
5. Use Firebase Rules Playground with the same user UID and document path to reproduce the denial.
6. Update either the document shape or the rule. Do not temporarily publish open rules on a production app.

"Audit these Firestore rules and this FlutterFlow query. Explain why the signed-in user receives permission-denied and propose the smallest safe rule or schema change. Rules/query: [paste error]."

For a deeper rules-first repair path, use our FlutterFlow Firestore rules fix. If you are building the Firebase setup from scratch, our guide to avoiding common Firebase integration mistakes in FlutterFlow explains the configuration mistakes that create these failures later.

When to call an expert: get help when the app has nested collections, admin roles, shared workspaces, or mixed public and private records, because small rule changes can expose data or block paying users.

4. API Call Returning an Error Only in Test or Released App

What it looks like: an API call works in the API tester but fails from Test Mode, web deploy, or the mobile app. The error may be 400, 401, 403, 404, 500, CORS, or a vague failed request message.

Why it happens: most often, the API tester is not sending the exact same request as the running app. Dynamic variables may be empty, headers may be missing, the base URL may point to staging, or JSON body types may change after binding a field. The second most common cause is a backend that rejects browser requests because CORS or origin checks are not configured.

Fix API failures:

1. Open DevTools Network, filter to Fetch/XHR, and click the failing request. Copy the URL, method, headers, request payload, and response body.
2. In FlutterFlow, open API Calls and compare the live request with the configured call, including auth headers and content type.
3. Check variables used in the request. Add temporary text widgets or logs to confirm IDs, tokens, and body fields are not null.
4. For 401 or 403, verify bearer token source, token refresh timing, and backend role permissions.
5. For 400, validate JSON types. Strings that look like numbers, UUIDs, or booleans may still be sent as strings.
6. For web-only CORS failures, fix the backend origin policy. This cannot be solved safely inside FlutterFlow alone.

"Compare this FlutterFlow API Call definition with the failing runtime request. Find missing headers, null variables, wrong JSON types, or CORS causes. Request/response: [paste error]."

Our focused guide to fixing FlutterFlow API integration errors in 2026 covers API Call setup in more detail. Here, the key is to trust the runtime Network tab over the green result in the API tester.

When to call an expert: escalate when the API affects billing, inventory, medical, legal, or customer data, or when the only apparent fix is exposing a secret key in the client.

5. App Store or Play Store Rejection

What it looks like: Apple or Google rejects the app after submission. The app may run fine on your device, but review flags login, privacy, crashes, metadata, permissions, account deletion, tracking, payment rules, or broken links.

Why it happens: most often, the build technically works but fails store policy. FlutterFlow apps are still native apps in review. They need correct package metadata, privacy disclosures, permission strings, account deletion flows, stable demo credentials, and compliant purchase behavior. The second common cause is a release-only crash caused by missing signing, Firebase, push notification, or asset setup.

Fix store rejection:

1. Read the rejection message line by line and separate policy issues from crash or build issues.
2. If reviewers cannot log in, create demo credentials and make sure the account has enough sample data to show the app's core flow.
3. In Settings and Integrations, check package name and app names under General > App Details, the launcher icon under General > App Assets, version and build number under App Settings > Mobile Deployment, and permission descriptions under Project Setup > Permissions.
4. Verify privacy policy, support URL, account deletion, and data collection answers match what the app actually does.
5. For crashes, reproduce on a clean device using the same release build, not preview or debug mode.
6. Submit a concise reviewer note explaining login steps and any required test account context.

"Turn this App Store or Play Store rejection into a fix checklist for a FlutterFlow app. Separate policy, metadata, permission, login, and crash causes. Rejection: [paste error]."

The longer store-specific process is in our FlutterFlow app store rejection guide. Use the rejection text as the source of truth, not forum guesses, because two similar rejections can require different changes.

When to call an expert: call in help when you have already been rejected more than once for the same issue, or when the fix touches payments, user-generated content, health claims, privacy, or account deletion.

6. App Lag and Jank as Lists Grow

What it looks like: the app feels slow after more users, records, images, or navigation paths are added. Scrolling stutters, pages take longer to open, or memory keeps climbing. FlutterFlow's own issue tracker documents this: On Data Change listeners are not cancelled on dispose, so a new listener is created every time the page is opened (flutterflow-issues 3341).

Why it happens: most often, the page fetches too much data at once or keeps live listeners open longer than needed. The second most common cause is rebuilding large widgets with image-heavy lists, nested components, or expensive conditional visibility. Another frequent cause is navigation that pushes the same page repeatedly instead of replacing or popping routes.

Fix FlutterFlow lag:

1. Find the slowest screen and list every backend query on that page, including queries inside components and nested list items.
2. Add pagination or query limits. Avoid loading entire collections into a page that only displays the first few records.
3. Prefer indexed queries with simple filters. In Firestore, create required composite indexes when the console reports them.
4. Compress images and use thumbnail-sized assets in lists instead of original uploads.
5. Audit navigation actions. Replace repeated push navigation with pop, replace, or clear-stack behavior where appropriate.
6. Remove unnecessary real-time updates from pages that do not need live data.

"Review this FlutterFlow screen for lag. Identify excessive queries, live listeners, large images, nested components, and navigation stack problems. Screen details: [paste error]."

For a deeper performance checklist, see our guide to FlutterFlow app lag fixes for 2026. The short version is simple: reduce live data, reduce widget work, reduce image weight, and keep navigation stacks under control.

When to call an expert: bring in help when performance problems appear only after real data is loaded, because the fix may require schema changes, denormalized summary records, indexes, or a selective export to native Flutter code.

7. Custom Action or Custom Code Failing to Compile

What it looks like: FlutterFlow shows Unknown error compiling custom code., a custom action disappears from the action picker, or export/build logs complain about imports, null safety, names, or missing files. A common cause is a widget or action whose name in the code does not match the name provided in the editor.

Why it happens: most often, the custom function, action, or widget violates the exact wrapper FlutterFlow expects. The second most common cause is a missing import or dependency version conflict. Another cause is referencing a FlutterFlow-generated file that is only generated when the related visual widget exists elsewhere in the project.

Fix custom code compile errors:

1. Open the custom code item and confirm the function, class, or widget name exactly matches the name shown in FlutterFlow.
2. Check every parameter type against FlutterFlow's configured inputs. Pay special attention to nullable values and lists.
3. Remove unused imports, then add only imports that are required by the code and available in the generated project.
4. Review custom dependencies in Custom Code settings. Avoid packages that conflict with FlutterFlow's pinned Flutter or Dart versions.
5. If an import like /flutter_flow/flutter_flow_google_map.dart fails, verify the related FlutterFlow widget is actually used or refactor the code to avoid that generated dependency.
6. Compile after each small change instead of pasting a large replacement.

"Debug this FlutterFlow custom code compile error. Check name matching, parameters, imports, nullable types, dependency versions, and generated FlutterFlow file references. Error/code: [paste error]."

This is one area where Dart and Flutter knowledge matters even if the app was built visually. FlutterFlow can generate the wrapper, but it cannot make incompatible code safe.

When to call an expert: call an expert when the custom code touches payments, maps, background tasks, native plugins, or generated files, because one bad dependency can block both web and mobile builds.

8. Supabase Type and UUID Mismatches

What it looks like: a Supabase query, insert, update, or RPC fails with errors such as invalid input syntax for type uuid, operator does not exist: uuid = text, or a blank result even though the row exists. FlutterFlow may show a generic API or backend query error.

Why it happens: most often, FlutterFlow sends a string, empty string, or nullable value into a Supabase column or filter that expects a real UUID. The second most common cause is schema drift after a column type changed but FlutterFlow's Supabase schema was not refreshed. Row Level Security can hide the same issue because denied rows look like empty results.

Fix Supabase UUID errors:

1. In Supabase, open the table definition and confirm the exact type of the failing column, especially uuid, text, and foreign keys.
2. In FlutterFlow, refresh the Supabase schema and reselect the table, columns, and filters used by the failing query.
3. Check the value being passed into the UUID filter. It must be a valid UUID string, not an empty string, display name, email, or document reference.
4. For inserts, let Supabase generate UUID primary keys when possible instead of passing client-generated placeholders.
5. Inspect RLS policies separately from type errors. A correct UUID can still return no rows if policy conditions reject the user.
6. Retest with one known row ID copied directly from Supabase.

"Find the UUID/type mismatch in this FlutterFlow Supabase query. Check schema sync, filter value, empty strings, RLS policy effects, and insert payload types. Error: [paste error]."

Use the full walkthrough in our guide to fixing FlutterFlow Supabase invalid UUID errors if you see the literal UUID syntax message. This error is usually fixable, but only if you verify both schema and runtime values.

When to call an expert: escalate when Supabase UUID errors overlap with auth, RLS, joins, or RPC functions, because changing column types after launch can break existing relationships.

9. Images or Assets Not Loading on Device

What it looks like: images show inside the FlutterFlow editor but are blank, broken, stretched, or missing on a real device. Sometimes the web app works but iOS or Android does not. Console or logs may show 404, storage permission errors, or asset bundle lookup failures.

Why it happens: most often, the image source is not available to the released app. Local design assets, Firebase Storage files, Supabase Storage objects, and remote URLs have different failure modes. The second most common cause is case-sensitive path mismatch. A file named Logo.png is not the same as logo.png on many production systems.

Fix missing images and assets:

1. Identify whether the image is a FlutterFlow uploaded asset, Firebase Storage file, Supabase Storage object, or remote URL.
2. For uploaded assets, confirm the asset is included in the project and not only pasted into a design preview.
3. For storage images, open the final URL in an incognito browser. If it fails there, the app cannot load it either.
4. Check Firebase Storage rules or Supabase bucket policies for public read access or signed URL requirements.
5. Rename files to lowercase, simple names without spaces, then update FlutterFlow references.
6. For list thumbnails, use resized images to reduce load time and avoid memory spikes on lower-end devices.

"Diagnose why these FlutterFlow images load in the editor but not on device. Check asset bundling, storage permissions, URL validity, filename case, and signed URL expiry. Details: [paste error]."

Asset issues often look like layout bugs, but they are usually path, permission, or file size problems. Test the real URL outside FlutterFlow first. If it does not load anonymously or with the correct signed access, the widget is not the root cause.

When to call an expert: call an expert when missing images are mixed with private user files, signed URLs, or uploads from multiple devices, because the right fix may require a storage policy and image processing workflow.

10. Exported Code That Will Not Build Locally

What it looks like: the app runs in FlutterFlow, but after code export a local build fails with dependency, Flutter SDK, iOS Pod, Android Gradle, package, or generated file errors. The founder expected export to be a clean handoff, but the local machine says otherwise.

Why it happens: most often, the local environment does not match the FlutterFlow-generated project's expected Flutter and Dart versions. The second most common cause is custom code or packages that FlutterFlow tolerated until the full native build process ran. iOS builds add CocoaPods, signing, and Xcode version constraints. Android builds add Gradle, Kotlin, Java, and signing constraints.

Fix local export build failures:

1. Read the first real error in the build log, not the final summary. Search for the earliest FAILURE, Because, error:, or missing package line.
2. Run flutter doctor and align Flutter, Dart, Xcode, Android Studio, Java, and CocoaPods with the exported project's requirements.
3. Run flutter clean, then flutter pub get, and fix dependency resolution before trying iOS or Android archives.
4. Review custom code and custom dependencies added in FlutterFlow. Remove or pin packages that conflict with generated dependencies.
5. For iOS, run pod install from the iOS folder and resolve signing separately from dependency errors.
6. Commit the exported code before editing generated files so you can separate environment fixes from code changes.

"Debug this exported FlutterFlow project build failure. Identify whether the root cause is Flutter SDK version, dependency conflict, custom code, CocoaPods, Gradle, signing, or generated files. Log: [paste error]."

Our FlutterFlow export code workflow explains what export really gives you and what still needs engineering cleanup. Export is useful, but it is not the same as receiving a maintained native codebase.

When to call an expert: call an expert when you need to keep building in FlutterFlow while also maintaining exported code, because two sources of truth can drift fast without a clear workflow.

When Self-Debugging Stops Making Sense

Most FlutterFlow errors above are fixable if you isolate the failing layer and make one controlled change at a time.

• The same bug returns after each FlutterFlow update. You may be depending on generated behavior, validation rules, or package versions that need a more stable architecture.
• Preview works but release fails. That usually means signing, environment, auth, store, or platform-specific config, not a widget issue.
• You are changing security rules blindly. Firestore rules, Supabase RLS, and storage policies protect real user data and should not be opened just to make a screen load.
• Performance fixes require schema changes. Pagination, indexes, denormalized records, and listener cleanup are engineering decisions, not cosmetic edits.
• Custom code blocks the build. Once dependencies, generated files, and native plugins are involved, visual debugging is no longer enough.
• The project has become harder to ship than to rebuild. Sometimes the correct answer is rescue, selective export, or a controlled migration, not another round of prompt-and-pray fixes.

AppStuck specialises in rescuing and completing FlutterFlow projects when the builder, backend, release process, or exported code has become tangled. AppStuck takes on FlutterFlow rescue and completion projects, and we will tell you honestly what your project needs and what it costs before any work starts.