Fly.io 503 Service Unavailable

How to fix it

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

1. 1. Find unhealthy Machines

   Copy steps
   1. Run fly status
   2. Run fly checks list; connection refused check errors may not appear in fly logs
   Did this fix it? Yes No

2. 2. Check autostart config

   1. If all Machines are stopped, confirm [http_service] or [[services]] exists and auto_start_machines = true
   Did this fix it? Yes No

3. 3. Check for outages

   Copy steps
   1. Open status.flyio.net
   2. Spread across regions: fly scale count 2 --region iad,ord
   Did this fix it? Yes No

Symptoms

Requests return 503 Service Unavailable; fly logs may show nothing.

Why it happens

• All Machines are stopped and autostart is not configured
• Health checks are failing on every Machine
• A regional issue

This guide also covers

• fly.io 503 service unavailable
• fly.io no healthy machines

Other Fly.io errors

• Fly.io: The app is not listening on the expected address and will not be reachable by fly-proxy
• Fly.io 502 Bad Gateway
• Fly.io Health Checks Failing
• Fly.io Machines Stopping or Not Starting (Auto-Stop)
• Fly.io Out of Memory (OOM Killed)
• Fly.io Deploy Failed: Waiting for Depot Builder, Registry 401, Too Many Requests
• Fly.io Certificate Not Issuing or Custom Domain Not Working
• How to Cancel Fly.io: Delete an App, Stop Billing and Delete Your Account