5 Deployment Errors That Break Every Vibe Coded App

You built something with an AI coding tool. It works perfectly in the preview. You hit deploy and... nothing. Or worse, some cryptic error you've never seen before.

I've watched this exact scenario play out hundreds of times. And it's almost always one of five things.

Why Do Missing Environment Variables Break Vibe-Coded Apps?

Missing environment variables are the single most common reason a vibe-coded app fails on deploy. AI coding tools like Bolt, Lovable, and Replit set up preview environments with sensible defaults baked in. But once you push to Vercel, Netlify, or Railway, those defaults vanish. Your Supabase URL? Gone. Your Stripe secret key? Never made it to production.

The fix is boring but important. Open your .env.local file and list every variable. Then go to your hosting platform's settings and confirm each one exists there too. Most platforms don't surface missing env vars cleanly. You'll get a generic "build failed" or a white screen when the real issue is a missing DATABASE_URL or NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY. And watch out for the NEXT_PUBLIC_ prefix in Next.js. If you forget it, client-side code silently gets undefined instead of your value.

What Causes Package Version Conflicts in AI-Generated Code?

Package version conflicts happen because AI coding tools install dependencies with loose version ranges, like ^2.0.0, which lets npm grab any minor or patch update automatically. Most of the time that's fine. But every few weeks, a package like next, tailwindcss, or @supabase/supabase-js pushes a breaking change and your tool grabs it on the next install.

The telltale sign? Your app worked yesterday, you changed nothing, and now it's broken. Look at your package.json. Find any package without a pinned version (no caret ^, no tilde ~). That's probably your culprit. Run npm ls to see exactly which versions got installed. Then pin the working version by replacing ^2.1.0 with 2.1.0. You can also commit your package-lock.json to lock everything down. Seriously, future you will thank present you. I've seen this break three Bolt apps in a single week.

Why Does My Vibe-Coded App Time Out During Build?

Build timeouts happen when your app exceeds the hosting platform's build window, which is typically 5 to 15 minutes depending on the provider. AI coding tools love generating code that does heavy lifting at build time, like fetching data from APIs during static site generation or processing large image assets. Add a bloated node_modules folder with 800+ packages and you're right at the edge.

I saw someone try to pre-render 2,000 product pages at build time on Vercel's free tier. Timed out every single time. The fix was switching to dynamic rendering with export const dynamic = 'force-dynamic' for anything over 50 pages. Not pretty, but it ships. Another common fix is moving API calls from getStaticProps to client-side fetching with useEffect or React Query. Also check if you accidentally installed heavy dev dependencies like Puppeteer or Sharp that inflate your build. Strip what you don't need.

Why Do CORS Errors Only Appear After Deploying My AI-Built App?

CORS errors appear after deployment because browsers enforce cross-origin restrictions differently for production domains than they do for localhost. When you're building with Cursor or Lovable, your preview environment runs on localhost where browsers are lenient. Deploy to myapp.vercel.app and suddenly every fetch request to an external API fails with "Access-Control-Allow-Origin" errors in the console.

This isn't specific to any AI tool. It's a fundamental web security rule. But AI coding tools make it easy to forget about because the preview hides the problem entirely. The fix depends on what you control. If you own the API, add the correct Access-Control-Allow-Origin header pointing to your production domain. If you don't own the API, create a serverless function (like a Next.js API route at /api/proxy) that makes the request server-side and returns the data to your frontend. Server-to-server calls skip CORS entirely. Never set the header to * in production with credentials.

Why Does My App Crash When the Database Migration Never Ran?

Database migration failures happen because production still has the old schema while your deployed code expects new columns or tables. You added a subscription_tier column to your users table locally using Supabase or Prisma. The AI tool generated code that reads from it. You pushed and deployed. Boom, column "subscription_tier" does not exist crashes your entire app.

Migrations don't run themselves. And AI coding tools like Bolt, Replit, and Cursor don't manage your production database schema for you. If you're using Prisma, you need to run npx prisma migrate deploy against your production database before deploying the code. For Supabase, apply your SQL migrations through the dashboard or CLI with supabase db push. A good habit is to always run migrations first, then deploy code. Never the other way around. And test the migration on a staging database if you can, because a bad migration on production can wipe data.

What Should You Do When You're Still Stuck After Trying Everything?

The honest answer is to stop debugging alone and get a second pair of eyes on it. Sometimes the bug isn't on this list. Sometimes it's a platform-specific edge case, a weird interaction between two packages, or something genuinely obscure that you'd never guess by reading docs.

That's exactly why we built VibeFix. Post your bug as a bounty, and a developer who's probably seen your exact error before will fix it. Most deployment issues get resolved within hours, not days. You describe what's broken, set a price, and a vetted developer picks it up. No hiring, no interviews, no back-and-forth on Upwork. Just a fix.

Stop banging your head against the wall. Post a bounty and get back to building the thing you actually care about.