Heroku H10 App Crashed Error

How to fix it

Try these in order — the most common fix is first.

1. 1. Read the crash reason in the logs

   Copy steps
   1. Run: heroku logs --tail -a <app>
   2. Look at the app[web.1] lines before the first H10: the stack trace names the failing file or module
   3. Fix that error locally and redeploy
   Did this fix it? Yes No

2. 2. Bind to the assigned port

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   1. Node: app.listen(process.env.PORT || 3000)
   2. Do not hard-code a port; Heroku assigns $PORT at boot
   3. Redeploy and check heroku ps
   Did this fix it? Yes No

3. 3. Check the Procfile and process type

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   1. Make sure Procfile is in the repo root, named exactly Procfile, with a line like web: node server.js
   2. Run heroku ps to see the process state (crashed vs up)
   Did this fix it? Yes No

4. 4. Compare config vars with local

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   1. Run heroku config -a <app>
   2. Add anything missing: heroku config:set KEY=value
   3. Missing DATABASE_URL or secrets are a common crash cause
   Did this fix it? Yes No

5. 5. Roll back a bad release

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   1. Run heroku releases
   2. Run heroku rollback v<N> to the last working release
   3. Then fix and redeploy
   Did this fix it? Yes No

6. 6. Reproduce production locally

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   1. Run heroku local web (needs a .env)
   2. Or NODE_ENV=production npm start for Node apps
   Did this fix it? Yes No

Symptoms

Browser shows 'Application error'; heroku logs show at=error code=H10 desc="App crashed" status=503.

Why it happens

• Exception at startup (missing module, gem or env var)
• Web process not binding to the $PORT Heroku assigns
• Wrong or missing Procfile web command
• Boot timeout or crash loop after a bad deploy
• Database or add-on config var missing

This guide also covers

• heroku h10 app crashed
• heroku h10 error
• heroku application error h10
• heroku app crashed

Other Heroku errors

• Heroku H12 Request Timeout Error
• Heroku R14 Memory Quota Exceeded Error
• Heroku Application Error Page
• Heroku Build Failed Error
• Heroku Git Push Rejected / Remote Rejected
• Heroku H14 No Web Dynos Running
• Heroku R10 Boot Timeout / H20 App Boot Timeout
• Heroku Custom Domain SSL Certificate Not Working