Fly.io Out of Memory (OOM Killed)

How to fix it

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

1. 1. Confirm OOM

   Copy steps
   1. Run fly machine status <machine-id> and look for OOM kill events
   2. Inspect usage with free or htop inside fly ssh console
   Did this fix it? Yes No

2. 2. Add memory

   Copy steps
   1. Run fly scale memory 512 (or higher)
   2. For CPU-heavy apps choose a larger Machine size
   Did this fix it? Yes No

Symptoms

Intermittent 502 errors, restarts, or a Machine that dies under load.

Why it happens

• Machine memory preset too small (shared-cpu-1x 256MB default size)
• Memory leak or large requests
• High CPU load alongside memory pressure

This guide also covers

• fly.io out of memory
• fly.io oom killed
• fly scale memory

The same problem in other apps

All slow, laggy or resource-hungry guides →

• DigitalOcean Droplet Out of Memory (OOM Killer) (DigitalOcean)

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 503 Service Unavailable
• Fly.io Health Checks Failing
• Fly.io Machines Stopping or Not Starting (Auto-Stop)
• 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