Fix · Vercel and deploying

Works in the preview link but not on production (or the other way)

Not checked against the vendor's current screens

What you may see

The preview deployment is fine and the real domain is broken
I see different data on preview and on the live site

Most likely cause

Preview and production are separate deployments with their own variables, and production only changes when a build from the production branch is promoted.

Check first (about two minutes)

In Vercel note which deployment the real domain points to (its time and branch).
Compare the Environment Variables per environment (Production versus Preview).

The fix prompt

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The exact error or what you see

What you did before it happened

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Prompt language

You are a patient senior engineer who deploys websites on Vercel every day and explains it to people who are not developers. I am not a developer, so explain every step in plain words and tell me exactly which button, menu or command you mean. If you are not sure about something, say so; do not guess.

Menu and button names change over time. If you cannot find a button or page I mention, say so and tell me what to look for instead of guessing.

THE PROBLEM
Works in the preview link but not on production (or the other way)

THE EXACT ERROR OR WHAT I SEE
[paste the exact error here]

WHAT I DID BEFORE IT HAPPENED
[write in a few words what you did before it happened]

MOST LIKELY CAUSE
Preview and production are separate deployments with their own variables, and production only changes when a build from the production branch is promoted.

DO THESE STEPS, IN THIS ORDER
1. Find which deployment (commit and branch) the production domain serves and which one the preview serves.
2. List the variables that differ between Production and Preview (names only) and what each one controls.
3. Explain how my change reaches production in this project (merge to the production branch, or promote a deployment), and do it only after I confirm.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- The production domain serves the same build as the preview I tested.
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not copy production secrets into preview or the reverse without asking.
- Anything I did not ask about: the design, the text, other pages, other settings or the data.
- Do not delete files, data or branches, do not reset or force-push, and do not rewrite history, unless you first show me exactly what would be lost and I say yes.
- Do not paste, print or ask me to paste a password or secret key into this chat. If one is needed, tell me which settings page of the right service to store it in.

WHEN YOU FINISH
Explain in simple words what you changed (file by file or setting by setting), why you changed it, and how I can undo it.

Paste it into Claude, ChatGPT, Gemini or Cursor, then follow what it says.

After you tried it, did it work?

Steps

Find which deployment (commit and branch) the production domain serves and which one the preview serves.
List the variables that differ between Production and Preview (names only) and what each one controls.
Explain how my change reaches production in this project (merge to the production branch, or promote a deployment), and do it only after I confirm.

Do not do this

Do not point a preview at the live customer database for testing.
Do not copy production secrets into preview or the reverse without asking.

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