Lovable + Supabase Not Working? Diagnose Auth, RLS, Database and Edge Functions

“Supabase is not working” is usually too broad a problem statement to fix safely.

A Lovable app connected to Supabase can fail in at least seven different places:

1. Authentication.
2. Database schema.
3. Table grants.
4. Row Level Security policies.
5. Storage policies.
6. Edge Functions or secrets.
7. Frontend state and environment configuration.

If you ask an AI builder to “fix Supabase” before identifying the failing layer, it may change several of them at once. That can make the visible error disappear while weakening the system underneath it.

I use Supabase in product work because Postgres, Auth and RLS can create a strong boundary between users and their data. The hard part is not connecting Supabase. It is preserving the business rule after the app becomes complicated.

Start by naming the exact failing action

Replace “Supabase doesn’t work” with a sentence like:

• A signed-in user cannot insert a record.
• User A can read User B’s orders.
• Login succeeds but the profile query returns nothing.
• An Edge Function works locally but fails in production.
• A storage upload returns 403.
• The database write succeeds but the UI never updates.

Now you have something testable.

Lovable’s official Supabase integration documentation confirms that the integration can involve database tables, authentication, storage, realtime and Edge Functions. Treat those as separate boundaries.

1. Is the user actually authenticated?

Check the current session before editing RLS.

Ask:

• Did sign-in succeed?
• Does the request carry a valid user session?
• Is the app querying before auth state finishes loading?
• Is the failing request running as anon or authenticated?

Supabase maps requests to database roles. Its current RLS documentation distinguishes unauthenticated anon requests from authenticated requests and notes that auth.uid() is null when there is no authenticated user.

A policy can be correct while the frontend is accidentally making the request unauthenticated.

2. Check table grants before rewriting policies

Supabase currently applies two layers of permission to exposed tables: grants decide whether a role can perform an operation at all, while RLS policies decide which rows that operation can touch.

That distinction is useful when you see a 42501 permission error.

If authenticated does not have the required table operation, changing the RLS expression will not help. If the grant is too broad and the policy is missing, the opposite problem can occur.

Do not “solve” the error by granting everything to everyone.

3. Test RLS as two different users

The minimum useful authorization test is not “my account works.”

It is:

• User A can perform the operation they should be allowed to perform.
• User A cannot access User B’s protected row.
• User B can access their own row.
• An unauthenticated request is denied where appropriate.

Supabase now explicitly recommends database tests for RLS and documents supabase test db with pgTAP. Its guidance says to assert both allow and deny cases for select, insert, update and delete where those operations exist.

That matches a principle I use in product work: permissions are not complete until the denied case is proven too.

4. Check using and with check separately

A policy that lets a user see a row is not automatically the right policy for creating or updating it.

For example:

• SELECT commonly uses using.
• INSERT commonly uses with check.
• UPDATE often needs both.
• DELETE commonly uses using.

Supabase’s official RLS guide documents those distinctions. This is one reason broad prompts such as “make this table private” can produce incomplete policies when the app has several operations.

Describe the business rule instead:

A tenant can read documents attached to their active tenancy, but cannot read another tenant’s documents and cannot change ownership.

The policy should implement that rule, not merely silence an error.

5. Check for service-role misuse

Supabase’s service role bypasses RLS and belongs on trusted server-side infrastructure.

If a browser request works only after someone inserted a service-role secret into frontend code, the app is not fixed. The authorization boundary has been bypassed.

Move privileged operations behind a trusted server or Edge Function and keep the secret out of the client.

6. Treat storage as its own permission system

A table insert can work while a file upload fails because Supabase Storage has its own policies and bucket configuration.

When uploads fail, capture:

• bucket;
• object path;
• current user;
• operation (insert/select/update/delete);
• exact status/error;
• relevant storage policy.

Do not keep changing database-table RLS when the failing request is against storage.

7. Treat Edge Functions as server code

If the browser reaches an Edge Function but the function fails, inspect function logs and secrets instead of changing the UI.

Check whether:

• required secrets exist in the deployed environment;
• the function is receiving the expected payload;
• the function validates the caller where required;
• an external API is returning an error;
• the frontend expects a response shape the function no longer returns.

This is particularly important for payments and email. A privileged operation should fail safely rather than fall back to client-side secrets.

A diagnostic matrix

The prompt I would give an AI coding agent

Give evidence, not permission to rewrite everything:

User A performs [exact action]. The request returns [status/error]. The relevant table/bucket/function is [name]. Expected rule: [business rule]. Current authenticated user is [state]. Inspect auth, grants and RLS separately. Do not disable RLS or expose service-role credentials. Identify the first failing boundary before proposing a change.

That keeps the agent focused on diagnosis.

When you should get a deeper audit

If the app has real users, payments or private records, and you cannot clearly explain who should be able to read and write each important resource, this has moved beyond “connect Supabase.”

Start with my AI-built app production checklist. You can also compare the platform trade-offs in Supabase vs Firebase.

If you have a Lovable/Supabase app where fixing one permission keeps breaking another workflow, I can help map the business rules first and then harden the implementation. Contact me.

Sources

• Lovable: Supabase integration
• Supabase: Row Level Security
• Supabase: Testing overview