fix guides
Fix guides
Last updated . Questions: hello@fixedlaunch.com
Each guide covers one broken flow in an AI-built app, with the causes to check in order and the signs that point to each.
Sign-in and accounts
- Supabase login works locally but fails in productionSupabase sign-in works on localhost or in the Lovable or Bolt preview, then fails on the live site. Five settings to check, in order, with the signs of each.
- Google sign-in redirect_uri_mismatch after deployGoogle sign-in works in the preview, then fails on your live domain with redirect_uri_mismatch. Five settings to check in Google Cloud and Supabase, in order.
- Firebase auth/unauthorized-domain after deployFirebase blocks sign-in on a domain it doesn't know. Add your live domain to Authorized domains, then check the authDomain in your config. Three steps.
- Supabase emails not sending to your usersSupabase sign-up, magic-link and reset emails fail for new users. The built-in sender reaches only your team, 2 an hour. Fix it with custom SMTP in five steps.
Data and Supabase
- Supabase data not saving, no errorYour app says saved but the Supabase table stays empty, and no error shows. Five causes to check in order, from Row Level Security to a missing sign-in.
- New row violates row-level security policy in SupabaseSupabase says new row violates row-level security policy and your save or upload fails. Five causes to check in order, with SQL policy fixes for each.
- Supabase Edge Function CORS error on your live siteYour live site can't call a Supabase Edge Function: CORS error, Failed to fetch or a preflight error. Four causes to check in order, with a Deno fix.
- supabaseUrl is required: blank page on your live siteYour live site shows a blank white page and the console says supabaseUrl is required. Four causes, in order, from a missing env var to a missed redeploy.
Publishing and the live site
- 404 on refresh on VercelYour Vercel site loads, then shows 404 NOT_FOUND when you refresh an inner page. Five checks for Vite, React Router, Lovable, Bolt and Next.js apps.
- Environment variable undefined in production on VercelA variable works in your preview but reads undefined on the live Vercel site. Four causes to check in order, each with its fix.
- Command "npm run build" exited with 1 on VercelVercel says Command "npm run build" exited with 1 when your app builds on your machine but fails on Vercel. Find the real error and fix it in six steps.
- Bolt app won't publishBolt won't publish your app, or the published site breaks. Five checks: build errors, build settings, environment variables, the Netlify link and Supabase URLs.
- Stripe webhook not working in productionStripe webhooks worked with the Stripe CLI locally and fail on the live site. Five causes to check in order: secret, mode, env var, raw body and endpoint URL.
- Lovable app not working: find the cause, then fix itLovable app not working? Start from your symptom: a blank screen, a preview that works while the live app breaks, or a failed publish. Fix steps for each.
Compare tools and fixes
- Lovable vs Bolt: plans, undo and what breaks on publishLovable vs Bolt: free-plan limits, Bolt's paid price from their pricing pages, how each one undoes a bad change, and where apps break when you publish.
- Replit vs Lovable: plans, undo and what breaks on publishReplit vs Lovable: Replit's paid plan prices, how each one undoes a bad change, and where apps break when you publish.
- Bolt.new pricing and what a fix costsBolt.new's Free plan is $0 and Pro is $18 a month, billed annually. Neither plan fixes a broken app. Here is what each costs, and what a FixedLaunch fix costs.
- Vibe coding cleanup: four ways to get a broken app fixedYour Lovable, Bolt, Cursor or v0 app is broken on the live site. Compare four ways to get it fixed, and what to send any helper.
- Hire a Lovable developer, or get a diagnosis first?Should you hire a Lovable developer or pay for a diagnosis first? When each route wins, what to ask before you pay, and what a diagnosis covers.
- Bug diagnosis vs full fix for an AI-built appA diagnosis looks into the bug and gives you a plan. A full fix changes the code and passes a test we agree first. Here is how to tell which one your app needs.
- v0 app shows 404 on refresh after deploying to VercelYour v0 app loads, then shows a 404 when you refresh a page or open a shared link on Vercel. Six causes in a Next.js app, in the order to check them all.
- Supabase RLS errors in AI-built apps, decodedEmpty lists, blocked saves, updates that do nothing, infinite recursion: what each Supabase Row Level Security error means and the policy that fixes it.
- Is my vibe-coded app secure? Seven checks before launchSeven security checks for an app built with Lovable, Bolt, v0 or Cursor before launch: leaked keys, Row Level Security, public buckets and admin pages.
- AI-built app works in preview but breaks when deployedYour Lovable, Bolt, v0 or Replit app works in the preview and breaks on the live site. Why the two differ, and the order to check settings, builds and data.
- How to hire someone to fix a Lovable, Bolt or v0 appA buyer's checklist for hiring help with a broken Lovable, Bolt or v0 app: what to write first, what to buy, where to look, what to ask and how to give access.
- Supabase AuthSessionMissingError: Auth session missingSupabase shows AuthSessionMissingError: Auth session missing! The app asked who is logged in and found nobody. Four checks to find out why, in order.
- Supabase Invalid Refresh Token: Refresh Token Not FoundSupabase shows Invalid Refresh Token: Refresh Token Not Found, or Already Used. Why a saved login stops working, with four fixes and the signs of each.
- Supabase says "Email not confirmed" when logging inSupabase says Email not confirmed when someone logs in. The account exists but the confirmation step never finished. Five checks, with the signs of each.
- Supabase "Email link is invalid or has expired"Supabase shows Email link is invalid or has expired, with error_code=otp_expired, after you click an email link. Why it happens and five fixes.
- TypeError: Failed to fetch with SupabaseTypeError: Failed to fetch means your app never reached Supabase. Five checks: the address, a paused project, missing variables, CORS and blockers.