Guide · Replit
Replit: your published app address does not load your app
Updated
Start with the simplest question: does the app work in Preview? If Preview does not display your app with a replit.dev URL, fix the app before publishing, because publishing will not fix a broken Preview. If Preview works, check the Logs tab in the Publishing pane for startup errors, missing packages or missing environment variables.
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Why it happens
Publishing turns your project into a public app, and the public address can behave differently from Preview. Before marking your app as live, Replit sends an HTTP request to it. If the homepage takes more than five seconds to respond, the health check can time out and publishing can fail at the final step. Other publishing-specific setup can also get in the way, such as the port configuration, production Secrets, the run and build commands, or a program that exits instead of running continuously.
Possible causes
- Preview itself is broken, so publishing cannot fix it.
- The program runs once and exits instead of starting a long-running process such as a web server.
- The server listens only on localhost or 127.0.0.1 instead of 0.0.0.0.
- Ports are specified in the .replit config, which disables automatic port detection, and the port is not set with externalPort at 80, so the promotion step does not pass.
- Secrets set in the Project Editor do not automatically carry over to the published app, so production Secrets are missing.
- The homepage takes more than five seconds to respond, so the health check can time out at the final step.
- Run or build commands have typos, incorrect flags or the wrong entry files.
Official fix steps
- Select Run at the top of the Project Editor and open Preview to confirm the app runs with a replit.dev URL. (docs.replit.com)
- Open the Logs tab in the Publishing pane and look for stack traces, missing packages, failed commands, missing environment variables or startup errors. (docs.replit.com)
- Review the run and build commands in the Publishing pane. If your app needs a build command and a start command, confirm both are correct. (docs.replit.com)
- Add all production Secrets and environment variables in the Publishing pane, since Secrets set in the Project Editor do not automatically carry over. (docs.replit.com)
- Make sure your application starts a long-running process such as a web server. (docs.replit.com)
- Check that the server listens on 0.0.0.0, and if ports are specified in the .replit config, specify a port with externalPort set to 80 and verify the server listens on the specified localPort. (docs.replit.com)
- If startup is slow, ask Agent to reduce startup work, move expensive work behind a user action, or cache data where appropriate. (docs.replit.com)
- Open Publishing and select Publish to trigger a new deployment. (docs.replit.com)
You can't see it yourself
You're signed in, your customers aren't. Your own account, preview or device is not a new customer's visit to the published address.
What to do next
App broke after you published it? Our AI agent fixes it in your code, then tests your live app again so you see the result yourself. The first check is free.
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Related: Works in the preview but not after publishing · Lovable publish not working: what is failing, and what a visitor sees when it "published" · My app is stuck on a loading spinner after I publish it
Sources
VibeFix's AI agent signs up to your live app like a new person and shows whether sign-up and your pages work. It may not show the published Replit address shows that the app is not live or not running directly.
Last checked: 31 October 2026, against the sources listed above.
VibeFix is independent. Lovable, Bolt, Replit, Base44, v0 and Supabase are trademarks of their owners.
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