Fix Lovable App Not Working: Rescue Your Lovable Build

You built something real in Lovable. It worked, preview looked clean, the demo went fine. Then you deployed it and something broke. A blank white screen. A login that spins forever. Data that just won’t show up. If this feels oddly specific, it’s because it’s a pattern, not bad luck, common enough by now that people in AI-builder communities just call it “works in the sandbox, dies on contact with real infrastructure.”

If your Lovable app isn’t working, the culprit is almost always one of five things: environment variables that never made it to your production host, Supabase Row-Level Security that’s disabled or missing policies, OAuth redirect URLs still pointing at localhost or the preview domain, a Stripe webhook registered against the wrong URL, or CORS rejecting requests from a real browser instead of the preview sandbox.

None of that is exotic, honestly. It’s just the normal gap between a dev sandbox and production, and it hits AI-generated apps harder than hand-coded ones for a simple reason: the AI writing your code has no idea your production domain even exists yet.

This guide walks through seven specific errors and exactly how to fix each one, explains why preview and production behave so differently in the first place, and tells you when it’s genuinely worth paying someone instead of losing a weekend to it. There’s also a prevention checklist at the end for your next build.

If you get partway through this and just want it fixed, KrishaWeb runs an AI Build Rescue service built for exactly this situation.

Why Lovable Apps Break in Production

Short version: preview and production aren’t the same environment, even though they feel identical while you’re building in them. Preview is forgiving about almost everything. Production checks all of it.

Here’s a data point that makes this more than a theoretical concern for Lovable specifically. In May 2025, security researcher Matt Palmer disclosed CVE-2025-48757 after going through 1,645 Lovable-built apps. He found that 170 of them, about one in ten, had Supabase tables that anyone could read without logging in, just by using the public anon key. That’s not a random bug that slipped through. It’s a structural consequence of generating a working schema before anyone’s actually thought about who should be allowed to see what.

Most “it worked yesterday” complaints boil down to one of five patterns:

• Missing environment variables. Whatever you set inside Lovable stays inside Lovable. It doesn’t magically show up on Vercel or Netlify.
• Supabase RLS left off. Tables Lovable creates land with RLS disabled unless someone flips it on manually, which is exactly the pattern behind that CVE above.
• Stale OAuth redirects. Still pointing at localhost or a preview subdomain instead of wherever the app actually lives now.
• Stripe webhooks aimed at the wrong place. Pointed at the preview URL, using test-mode secrets, so nothing fires once you go live.
• CORS blocking legitimate traffic. Edge Functions or third-party APIs reject requests because nobody updated the list of allowed origins.

7 Common Lovable Errors & How to Fix Them

Error 1: Missing Environment Variables in Production

You deploy, and instead of your app, you get a blank white screen. Pop open the console and you’ll likely see something like “VITE_SUPABASE_URL is undefined.” Preview link still works fine, by the way, it’s just your actual custom domain that’s dead.

The reason is almost boring: variables you set inside Lovable’s own settings never automatically travel to whatever’s actually hosting your deployed app.

Fix it like this:

1. In Lovable, go to Settings, then Environment Variables, and write down everything there, especially VITE_SUPABASE_URL and VITE_SUPABASE_ANON_KEY.

2. Open your hosting dashboard, Vercel, Netlify, wherever you actually deployed.

3. Add every variable there using production values, not whatever was sitting in preview.

4. For the Supabase pair specifically, VITE_SUPABASE_URL is your project URL, and VITE_SUPABASE_ANON_KEY lives under Supabase’s Settings, then API.

5. Redeploy.

6. Hard-refresh the browser (Ctrl+Shift+R or Cmd+Shift+R) so you’re not staring at a cached failure and panicking for no reason.

Going forward, keep a .env.example file in your repo listing every variable the app actually needs. Cheap insurance.

If you’ve genuinely added everything you can think of and it’s still broken, that usually means there’s a second issue hiding behind this one, which is worth a quick professional look rather than another hour of guessing.

Error 2: Supabase Row-Level Security Disabled

This one shows up as 403s. You’ll see console messages like “permission denied for table” or “new row violates row-level security policy,” and data that loads fine in preview but comes up empty in production.

Lovable generates your table schema without turning RLS on. That’s just the default state for any new Supabase table unless somebody explicitly flips the switch, and it’s the exact vulnerability class from the CVE mentioned above.

Here’s the fix. In the Supabase dashboard, go to Table Editor, click into your table, open the Policies tab. No policies listed means RLS is off. Turn it on:

ALTER TABLE your_table ENABLE ROW LEVEL SECURITY;

Then add a policy for each operation you actually need, scoped to whoever’s signed in:

CREATE POLICY “Users read own data”
ON your_table
FOR SELECT
USING (auth.uid() = user_id);
 
CREATE POLICY “Users insert own data”
ON your_table
FOR INSERT
WITH CHECK (auth.uid() = user_id);
 
CREATE POLICY “Users update own data”
ON your_table
FOR UPDATE
USING (auth.uid() = user_id);
 
CREATE POLICY “Users delete own data”
ON your_table
FOR DELETE
USING (auth.uid() = user_id);

Do this for every table with a user_id column.

Quick warning here, because it trips people up constantly: turning on RLS without writing any policies doesn’t secure anything, it just blocks everyone except the service role. That’s usually why someone reports “I enabled RLS and the app broke.” The answer isn’t to switch it back off. It’s to actually write the policies.

You can also just ask Lovable to do it, something like “enable Row Level Security on all tables and create policies so users can only access their own records” tends to get a decent first pass, though I’d still check the generated SQL against your actual data model before trusting it blindly.

Audit this before you deploy, not after. Every table touching user data needs four policies, each genuinely referencing auth.uid(), not just present for show.

Got ten-plus tables with real relationships between them? That’s a genuine audit at that point, worth a second set of eyes before real user data is anywhere near exposed.

Error 3: OAuth Redirect URL Still Points to Localhost

Login works great in preview, then fails the moment you deploy. You’ll get something like “redirect_uri_mismatch” or “Invalid redirect URL,” and nobody can sign in with Google, GitHub, or whatever you’re using.

The redirect URLs configured in Supabase and in your OAuth provider are still pointing at localhost or your Lovable preview domain, not wherever the app actually lives now.

To fix it:

1. In Supabase, go to Authentication, then URL Configuration. Set the Site URL to your real domain, https://yourapp.com, no trailing slash. Under Redirect URLs, add https://yourapp.com/** and https://yourapp.com/auth/callback.

2. In your OAuth provider’s console, Google Cloud Console, GitHub’s settings, wherever, add both https://<your-project-ref>.supabase.co/auth/v1/callback and https://yourapp.com/auth/callback as authorized redirect URIs.

3. Save it all and redeploy.

4. Test with an actual login attempt, not the preview flow.

Write down every redirect URL you configure, for every provider, in a README before you deploy. Takes two minutes now, saves you re-discovering all this from scratch the next time you add a provider.

Juggling redirects across three or four OAuth providers at once gets error-prone fast. A rescue team can usually sort and verify all of it inside an hour.

Error 4: Stripe Webhook Registered Against the Preview URL

Payments work in test mode, then fail once you’re live. Webhook errors read “Invalid signature” or “Webhook endpoint not found,” and orders just… don’t update after a successful charge.

The webhook’s still pointed at your Lovable preview URL with a test-mode secret, not your live production URL with a live-mode secret.

1. In the Stripe dashboard, go to Developers, then Webhooks, and remove the old endpoint pointing at the preview URL.

2. Add a new endpoint pointing at your actual production URL, something like https://yourapp.com/api/webhooks/stripe.

3. Switch from test mode to live mode.

4. Update STRIPE_WEBHOOK_SECRET in your environment variables to whatever production secret Stripe gives you.

5. Redeploy and test with a real transaction.

Keep test and production as genuinely separate Stripe projects instead of flipping one project back and forth between modes. Much harder to mix up that way.

I’d treat this one as urgent rather than something to sit on. A broken webhook means silent order failures, and once real money is moving through the app, it’s worth having someone check the whole Stripe integration, PCI handling included, not just the webhook.

Error 5: CORS Errors on External API Calls

Console shows something like “has been blocked by CORS policy.” The API call worked fine in preview, dies once deployed, and the network tab is full of failed requests.

Supabase Edge Functions and third-party APIs usually ship with loose CORS settings during development. Production tightens up, and if nobody updated the list of allowed origins to include your real domain, the browser blocks the request before it even reaches your server.

Find the specific endpoint failing, from the console error. If it’s your own Supabase Edge Function, add the right headers:

return new Response(JSON.stringify(data), {
  headers: {
    ‘Access-Control-Allow-Origin’: ‘https://yourapp.com’,
    ‘Access-Control-Allow-Methods’: ‘GET, POST, PUT, DELETE’,
    ‘Access-Control-Allow-Headers’: ‘Content-Type, Authorization’,
  },
});

If it’s a third-party API you don’t control, ask them to whitelist your production domain, or route the call through your own Edge Function so the browser never talks to that third party directly. Redeploy, retest.

Never put API secrets in client-side code. Anything sensitive belongs behind a server-side Edge Function, which conveniently sidesteps most CORS headaches too.

If you’re juggling several external APIs, each with its own CORS quirks, that can eat a full day of trial and error on your own. A rescue engagement usually maps and fixes all of them in a single pass.

Error 6: Database Migrations Never Ran in Production

Console says something like “relation ‘your_table’ does not exist.” The app works fine in preview, but production is just missing the table entirely, so any new feature you built simply isn’t there.

Here’s what happened: the migration Lovable generated when you built that feature in preview never actually got run against your production Supabase instance. Preview and production are separate databases. A schema change in one doesn’t magically appear in the other.

1. In Lovable, export the migration script (Settings, then Database, then Export Migrations).

2. Open the SQL Editor in your Supabase dashboard.

3. Paste in the migration, run it.

4. Confirm the tables now exist in the Table Editor.

5. Redeploy.

If that feels murky, you can ask Lovable to “create a fresh Supabase migration script for all tables and run it against production,” but eyeball the generated SQL first, especially if this touches a live database with real data in it.

Make running migrations against production a required step in your deploy process, not something you remember to do after the fact.

If the migration touches existing data rather than just adding new tables, and you’re at all worried about losing something, get someone experienced to run it. That’s not the moment to test your backup strategy for the first time.

Error 7: Build Fails or the App Won’t Compile

You get “Failed to compile,” a pile of TypeScript errors, and the app simply refuses to deploy no matter how many times you hit the button.

Somewhere along the way, a manual edit or an AI-generated change introduced invalid syntax or a type mismatch that the editor let slide but a strict production build won’t.

1. Open Lovable’s History panel.

2. Roll back to the last version you know actually worked.

3. Reapply your changes one at a time, testing after each, not all at once.

4. Open the browser console (F12) and read the real error, not just the summary line.

5. Fix the first error, not the last. Later errors are usually just noise cascading from the first one.

6. If generation stopped mid-way because you ran out of credits, wait for them to refresh (or upgrade), then give one narrow prompt to finish just the interrupted file.

Keep prompts narrow, and check the history after each one instead of hand-editing code at the same time the AI is generating changes. Mixing the two is where most of these breakages actually start.

If enough edits have piled up that you honestly can’t tell what broke it anymore, that’s a fair time to bring in someone who can diff the history and isolate the actual regression instead of guessing alongside you.

Why Preview Works But Production Fails

Worth spelling out plainly, since it’s the source of most of the confusion here: the editor you’re building in runs on different environment variables, permissions, and validation rules than the app you actually ship.

• Preview auto-injects Lovable’s own variables; production needs them configured manually on your host.
• Preview often has RLS switched off for convenience; production needs it on, with policies that mean something.
• Preview points at localhost or the preview domain; production needs every redirect URL updated to match reality.
• Preview’s CORS is loose; production enforces it properly, which is a good thing, but it also means requests that worked a minute ago can suddenly fail the moment you deploy.
• Preview sometimes auto-applies migrations; production makes you run them yourself.
• Preview lets TypeScript issues slide; a production build checks types strictly and won’t compile around them.
• Preview runs on test-mode API keys; production needs the real, live secrets.

None of this means Lovable’s broken. It means the editor and the deployed app are, structurally, two different environments, and treating a passing preview as proof the thing is production-ready is the actual mistake behind most “it worked five minutes ago” moments.

When to Hire Professional Rescue

DIY is fine for one isolated error. It gets a lot less fun once several of these stack on top of each other, which happens more than you’d expect, because they cluster. Fix the environment variables and the RLS problem underneath often surfaces right after.

A few situations where paying someone genuinely beats burning a weekend on it:

• Three or more distinct errors at once. Untangling RLS, env vars, OAuth, and CORS one at a time, without knowing which is masking another, eats days. A focused rescue usually clears all of it in a matter of hours.
• A deadline that actually matters. An investor demo or a launch date doesn’t care how close you are.
• Genuinely complex integrations. ERP, PIM, CRM, or custom API work goes faster with someone who’s already solved that exact pattern.
• Real data-loss risk. Restructuring a live database with no safety net is exactly where things go sideways.
• An actual security concern. Exposed keys, half-configured RLS, missing auth, none of that should sit unresolved.
• You’ve already tried the obvious fixes. At some point more guessing isn’t the right next move.

What KrishaWeb’s AI Build Rescue actually does

We built this because “my Lovable app broke and I have no idea why” turned out to be something we saw over and over, not a rare event. The engagement generally includes:

• A rapid diagnosis, usually within an hour, that catches everything actually wrong, not just the one symptom you happened to notice
• Fixes for RLS, environment variables, OAuth, CORS, migrations, and build errors, all handled in one pass
• A real security audit confirming the app is production-ready, not just working again
• Documentation of what broke and why, so you’re not back here in a month
• Ongoing support if you want it, for teams planning to keep shipping fast with Lovable

Most of these run one to two business days: roughly an hour to diagnose, four to six hours for the standard fixes, another two to three for a proper security pass. Pricing depends on scope, usually somewhere between $2,000 and $10,000, and we’ll give you a real number once we’ve actually looked at what’s wrong.

Prevention Checklist for Future Builds

Most of this is preventable with maybe twenty minutes of deliberate checking before you deploy:

• Environment variables. Keep a .env.example file listing everything the app needs, and set both build-time and runtime variables on your actual hosting provider, not just inside Lovable.
• Supabase RLS. Enable it on every table touching user data, all four policies, all scoped to auth.uid().
• OAuth redirect URLs. Set your Site URL to the production domain and add matching redirect URLs everywhere they’re needed.
• Stripe webhooks. Point them at production with live-mode secrets, and keep test and production as separate projects.
• CORS. Configure it on every Edge Function and external API call, and never hardcode secrets into client-side code.
• Database migrations. Run every migration against production before you consider a feature actually shipped.
• Build validation. Test the production build locally before deploying, and clear TypeScript errors instead of letting the editor’s leniency mask them.
• Security audit. Check for exposed keys, disabled RLS, and missing auth before calling anything launch-ready. Given how common CVE-2025-48757-style leaks turned out to be, skip this at your own risk.
• Backups. Export your database before any major change, and actually test that rollback works, not just that it exists on paper.
• Documentation. Write down every integration, environment variable, and deployment step somewhere you’ll actually find it again later.

Frequently Asked Questions

Conclusion

Lovable apps break in production for a small, predictable set of reasons: environment variables that didn’t travel with the deploy, RLS that’s off or missing policies, OAuth redirects still stuck on localhost, Stripe webhooks aimed at the wrong URL, CORS blocking traffic that sailed through fine in the sandbox. Most single-issue cases, the fixes above will handle on their own.

It gets harder once several of these stack together, or there’s a real deadline, real money moving through Stripe, or user data sitting behind an RLS policy that may or may not actually be doing its job. That’s usually where DIY stops being the faster option.

Your Lovable app is broken. What now?

Fix it yourself. Work through the errors above in order, and test after each change, not at the end.

Get it fixed. Book a call with KrishaWeb’s AI Build Rescue team and have it diagnosed and repaired in one to two business days.

A broken app in front of a customer or an investor costs more than the fix does.

Nirav Panchal

Lead – Custom Development

Lead of the Custom Development team at KrishaWeb, holds AWS certification and excels as a Team Leader. Renowned for his expertise in Laravel and React development. With expertise in cloud solutions, he leads with innovation and technical excellence.

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