Your AI builder's preview works, but the public link is blank, shows an error, or loses data. That does not mean you need to rebuild the whole app. It means the preview and the live version differ somewhere.
Find the first broken layer—publishing, settings, addresses, storage, or the running app—and change one thing at a time.
Did publishing fail, or does the live app fail?
First check the release status. If it says error, open the publishing log—a record of what happened—and find the first clear failure. One missing software package, wrong setting name, or wrong project folder can cause many later error messages.
In the JustDeploy project's Deployments list, find the intended version and check for Live. An older version can say Ready without serving visitors. Open the public address before assuming that a successful build fixed the customer problem.
For an error in the running app, open Advanced → Logs. Repeat the broken action once and note the time. Do not click Rebuild or Redeploy just to inspect a problem; those actions change the deployment.
Can a clean copy produce the same result?
A preview may quietly reuse old files, saved browser data, or tools installed on your computer. Ask your coding AI to start from a fresh copy with none of those hidden extras. Then have it test the version meant for the public.
How to check
- Start from a clean copy of the project.
- Install only the software add-ons listed by the project.
- Create and start the version meant for the public.
- Open it in a private browsing window.
- Paste a direct page address and refresh it.
Are the live settings present?
Private keys and other per-project values usually live in the host's protected settings, often called environment variables. A value may be missing, misspelled, saved on another project, or added after the current release was created.
On JustDeploy, publish again after changing one of these settings. Ask the app to report the name of a missing setting, never its private value.
Does anything still point to your own computer?
Search for localhost, preview links, private network addresses, and numbers such as :3000 used by a local preview. In a published app, localhost means the hosted app itself—not your laptop.
Also update the approved addresses in your login, payment, and email services. If a service sends messages back to your app through a webhook, update that address too. A service may accept the preview address but reject a new public domain until you add it.
Is the app saving data in a temporary place?
Files written beside the running app can disappear after a restart or update. Put customer records in a database and uploads in durable file storage. Use local files only for work that can be safely discarded.
If a customer expects to find it tomorrow, it should not depend on today's running process.
Can you follow one failure in the logs?
Create the error again and note the exact time, page, and action. Search a narrow log window for that request. A useful entry names the action, result, and tracking number for the request. It also shows how long the action took and any error code from an outside service.
Do not log passwords, private keys, full payment details, or unnecessary personal data. The goal is to identify the failing layer without creating a second security problem.
What does the symptom suggest?
| What you see | Check next |
|---|---|
| A page works until you refresh it | Settings for direct page links and the public version |
| A blank page with a browser error | Public settings, browser code, and image or file paths |
| One action returns a server error | A missing private setting, a failed database request, or an outside service |
| An upload disappears later | Temporary local files used instead of durable storage |
| A request sometimes times out | A slow outside service, no time limit, or data kept inside only one running copy |
How do you know the fix is real?
- Write down the failed action and current release name or number.
- Make the smallest change supported by the evidence.
- Publish a new release if code or settings changed.
- Wait until it is live, then repeat the exact same action.
- Add a check that would catch the problem before the next launch.
A useful fix explains why the live app differed from the preview. Changing many unrelated things may hide the error today and make the next problem harder to understand.
What should you read next?
If the clean production version passes, follow the JustDeploy troubleshooting guide for platform-specific checks.