Why FlutterFlow + Supabase Integrations Break
FlutterFlow's Supabase integration is powerful - but the combination of Supabase's V2 migration, Row Level Security policies, and FlutterFlow's code generation creates a unique set of failure modes that are difficult to debug from the FlutterFlow UI alone.
As engineers who specialize in FlutterFlow rescue, we've compiled every Supabase integration error we've encountered.
The Top 6 Supabase Integration Errors
1. Supabase V2 Breaking Changes
Symptom: Custom functions that worked previously now throw compilation errors.
Cause: FlutterFlow updated its Supabase package from V1 to V2. The .on() method for real-time changes was replaced with .onPostgresChanges() and .onBroadcast().
Fix: Review all custom functions that use Supabase real-time listeners. Replace .on('postgres_changes', ...) with .onPostgresChanges(event: PostgresChangeEvent.all, ...). Check the Supabase Dart V2 docs for all breaking changes.
2. async/await Compilation Errors
Symptom: Custom function fails to compile with "await expression can only be used in an async function" error.
Cause: All Supabase operations are asynchronous, but FlutterFlow's custom function editor doesn't always add the async keyword.
Fix: make sure your function signature includes async: Future<List<active>> fetchData() async { ... }. In FlutterFlow's custom function editor, toggle the function to 'Async' mode if the option is available.
3. Row Level Security (RLS) Blocking Queries
Symptom: Queries return empty results even though data exists in the table.
Cause: Supabase RLS is enabled by default on new tables. Without explicit policies, no data is accessible - even to authenticated users.
Fix: In Supabase Dashboard → Table Editor → your table → RLS Policies, add policies for SELECT, INSERT, UPDATE, DELETE. A basic authenticated-user policy: auth.uid() IS NOT NULL. For user-specific data: auth.uid() = user_id.
4. Real-Time Listeners Not Firing
Symptom: Changes to the database don't update the UI in real-time.
Cause: Supabase real-time requires: (1) the table must have REPLICA IDENTITY set, (2) the table must be added to the supabase_realtime publication, and (3) RLS policies must allow the subscribing user to see the data.
Fix: In Supabase SQL Editor, run: ALTER TABLE your_table REPLICA IDENTITY FULL; and ALTER PUBLICATION supabase_realtime ADD TABLE your_table;. Verify RLS policies include the authenticated user.
5. Auth State Not Persisting
Symptom: Users are logged out every time they close and reopen the app.
Cause: FlutterFlow's Supabase auth initialization may not be correctly configured to persist the session token.
Fix: In FlutterFlow's Supabase settings, make sure 'Persist Auth' is enabled. In custom code, verify that Supabase.initialize() is called with authFlowType: AuthFlowType.pkce for web apps. Check that your Supabase project's JWT expiry isn't set too short (default: 3600 seconds).
6. Foreign Key Joins Returning Null
Symptom: Queries with .select('*, profiles(*)') return null for the joined table.
Cause: The foreign key relationship isn't properly defined in Supabase, or the column name doesn't match.
Fix: Verify the foreign key exists in Supabase Table Editor. The join syntax requires the foreign key column to reference the joined table's primary key. Use .select('*, profiles!user_id(*)') to explicitly specify the foreign key column if there are multiple references.
Supabase vs Firebase for FlutterFlow
| Factor | Supabase | Firebase |
|---|---|---|
| Database type | PostgreSQL (relational) | Firestore (document) |
| Query flexibility | Full SQL support | Limited compound queries |
| Real-time | Postgres CDC + Broadcast | Native snapshot listeners |
| Auth | Built-in with RLS | Firebase Auth + Security Rules |
| FlutterFlow support | Good (improving) | Excellent (native integration) |
| Pricing | Generous free tier | Pay-as-you-go after free tier |
| Best for | Complex queries, SQL familiarity | Real-time apps, rapid prototyping |
Need Expert Help?
Supabase integration issues compound quickly. One misconfigured RLS policy can block your entire app. Rehost fixes FlutterFlow + Supabase architectures - from RLS policy design to real-time optimization. Start your free audit →
FAQ
Why does my Supabase query return empty in FlutterFlow?
The most common cause is Row Level Security. Check that your table has RLS policies allowing the authenticated user to SELECT data. In Supabase Dashboard, temporarily disable RLS on the table to confirm this is the issue.
Should I use Supabase or Firebase with FlutterFlow?
Use Firebase if you need real-time syncing and rapid prototyping - it has deeper FlutterFlow integration. Use Supabase if you need complex relational queries, full SQL access, or are more comfortable with PostgreSQL.