Vibe Coder Daily

lovable June 27, 2026 · 6 min read

Lovable app not saving data? The Supabase checklist

Lovable app not saving data or stuck in an auth loop? It's almost always one of three Supabase issues. Here's how to check each one and fix it.

You fill out the form, click save, get a success toast — and reload the page to find nothing actually saved. Or you sign in, land on the dashboard for half a second, and get bounced right back to the login screen. No error message, no obvious clue.

If you searched “lovable data not saving,” “lovable supabase not working,” or “lovable auth loop,” you’re not imagining it. Lovable builds its backend on Supabase under the hood, and by a lot of user reports, this exact category of bug — data silently not persisting, or auth loops on sign-in — shows up in a large share of projects. The good news: it’s almost always one of three specific things, and all three are checkable in a few minutes.

Why this happens

Lovable is very good at generating a UI that looks fully wired up — the form, the button, the success toast — because that’s the part it can render and preview instantly. Whether that button actually talks to your database is a separate, less visible layer, and that’s where these bugs live. Three causes cover almost every case:

  1. The UI was never actually wired to Supabase. The form submits, a success state fires in the frontend code, but the insert/update call to Supabase either wasn’t generated or is silently failing. The success toast is real — it’s just responding to the form submission, not to a confirmed database write.
  2. Row-level security (RLS) is blocking the write. Supabase ships with RLS enabled by default on new tables, and until a policy explicitly allows a given operation, Supabase rejects it. This rejection is often swallowed by the frontend instead of surfaced to you, so it looks like nothing happened rather than looking like an error.
  3. Auth is misconfigured. Wrong redirect URLs or an email-confirmation setting that doesn’t match how your app expects users to sign in will cause Supabase to hand back a session that your app doesn’t recognize as valid — so it sends the user back to login. That’s the loop.

None of these mean your app is broken beyond repair. They mean one specific connection — write, permission, or auth handshake — isn’t wired the way your UI assumes it is.

How to check each one

You don’t need to be a Supabase power user for this — you’re just looking in three specific places.

1. Check if the write is actually happening.

  • Open your Supabase project dashboard → Table Editor → the table your form should be writing to.
  • Submit the form in your app, then refresh the table view. If no new row appears (and no error showed in your app), the write likely isn’t happening at all.
  • Also open your browser’s dev tools → Network tab, submit again, and look for a request to a supabase.co URL. If you don’t see one, the frontend never called Supabase — the “save” button is only updating local UI state.

2. Check for a blocked RLS write.

  • Still in the Network tab, look at that same Supabase request. A write blocked by RLS typically returns a 401 or 403 response, sometimes with a body mentioning “row-level security policy” or “permission denied.”
  • In the Supabase dashboard, go to Authentication → Policies (or Table Editor → your table → RLS tab) and check whether policies exist for INSERT and UPDATE on that table. If the table shows RLS enabled with no matching policy, that’s your blocker — Supabase’s default is to deny, not allow.

3. Check auth configuration for the loop.

  • In the Supabase dashboard, go to Authentication → URL Configuration and confirm the Site URL and Redirect URLs match the actual domain your app is running on (including your Lovable preview URL if that’s where you’re testing).
  • Go to Authentication → Providers → Email and check whether Confirm email is turned on. If it’s on but your app’s flow doesn’t handle the “check your email” step, users can get a session that never fully confirms — which reads as a loop back to login.

The fix — per cause

If the write was never wired up: this is a code-generation gap, and it belongs in a fix request to Lovable, not in the Supabase dashboard. Don’t just say “the save button doesn’t work” — that’s vague enough that Lovable’s generic “Try to Fix” retry will burn a few credits without addressing the actual gap. Instead, name the file, the action, and the missing piece: “In ContactForm.tsx, the submit handler shows a success toast but never calls Supabase to insert the row into the contacts table — add the actual insert call and only show success after it resolves.” This is the kind of precise, scoped fix request that Traileo is built to generate automatically from pointing at the broken element in your live app, if you’d rather not write it out by hand each time.

If RLS is blocking the write: this one you fix directly in Supabase, not through Lovable. Go to Authentication → Policies, add a policy for the operation that’s missing (commonly INSERT or UPDATE) scoped to the right condition — for most single-user apps, something like “user can insert/update rows where user_id matches auth.uid().” If you’re not sure what condition your app needs, check how the table’s user_id (or equivalent) column gets populated in your insert call, and match the policy to that.

If auth is misconfigured: fix the Site URL and Redirect URLs in Supabase to exactly match your live/preview domain (including protocol — https:// vs http:// mismatches count). If email confirmation is the issue and your app doesn’t have a “confirmation pending” UI, either turn off Confirm email for now (fine for early builds) or ask Lovable to add a confirmation-pending screen — again naming it directly: “After sign-up, show a ‘check your email to confirm’ screen instead of redirecting to the dashboard, since email confirmation is required.”

How to verify the fix actually landed

Don’t trust the success toast — that’s the exact thing that was lying to you before.

  1. Submit the form again and check the Supabase Table Editor directly for the new/updated row, not just the app’s UI response.
  2. Re-check the Network tab request: confirm it’s now returning a 200/201 instead of a 401/403.
  3. For the auth loop, sign in from a fresh incognito window (no cached session) and confirm you land on the dashboard and stay there after a manual refresh — not just immediately after login.
  4. If you added an RLS policy, test with a second test account too, not just your own — a policy that works for the user who created it can still fail for everyone else if the condition was scoped too narrowly.