Instance reachability check failed ☁️ AWS

EC2 status check failed: Instance reachability check failed (1/2 checks passed)

AWS can reach the host, but the operating system inside the instance isn’t responding — kernel panic, full disk, broken network config or exhausted memory.

Seen on: AWS

Meaning

System checks failing point to AWS hardware; instance checks failing point to the OS. The system log/screenshot shows boot errors like fstab mistakes (a missing volume with no nofail), kernel panics, or OOM.

Common causes

  • Bad /etc/fstab entry (volume detached, no nofail)
  • OS out of memory/disk
  • Kernel or network config change
  • Firewall/sshd config breaking boot

⚡ Quick fix

  1. Get the console output/screenshot
  2. Reboot; if it persists, stop/start (moves to new hardware)
  3. Detach the root volume, attach to a rescue instance and fix the config

Detailed fix by platform

AWS CLI

  1. bash
    aws ec2 get-console-output --instance-id i-0abc --latest --output text | tail -50
aws ec2 get-console-screenshot --instance-id i-0abc --query ImageData --output text | base64 -d > shot.jpg

How to diagnose

  1. Which check — System vs instance
  2. Console — Boot errors
  3. Recent changes — fstab, kernel, firewall

🔧 Still not fixed?

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