A service that runs fine on your own machine can go blank or throw errors the moment it is deployed. This is the single most common problem in vibe-coded projects, and the causes repeat. Work through these seven in order and most cases resolve.

Why do local and production behave differently?

Your machine has accumulated settings and files while you worked, while a deployment server starts empty every time. Anything that exists only on your machine becomes a break point. So the question to ask first is always: what is missing on the server?

The seven things to check, in order

  1. Environment variables registered on the server: .env files are not uploaded, so they must be entered in your hosting dashboard separately.
  2. File name casing: macOS and Windows ignore case, Linux servers do not. Header.tsx and header.tsx are different files in production.
  3. The build actually succeeded: read the build log to the end. Red output means what is live is the previous version.
  4. External services know the new address: add your deployed domain to the allowed origins of your payment, auth, and database providers.
  5. You are not still using test keys: many providers issue separate test and live credentials.
  6. No library is missing from the manifest: something installed locally but never recorded will not exist on the server.
  7. No browser-only code runs on the server: touching window or localStorage during server rendering halts the page.

How do you find the cause fastest?

Two places tell you almost everything: your host build log and the browser console (F12). If the page is blank, the first red line in the console is the culprit. Copy that exact line into your AI and ask why it only appears in production and how to fix it.

Every deployment reassembles the project from scratch. The fewer things that exist only on your machine, the fewer deployment failures you will have.

We publish a free checklist covering everything to verify before launch, including these seven. It runs to nine chapters across security, privacy, performance, and payments, with a copy-paste AI prompt attached to each item.