Troubleshooting Windows – Enabling DHCP through offline registry edit

Today, the main task was to troubleshoot why a specific Windows AMI was unable to launch and pass health checks.

Ultimately, the best way to troubleshoot issues where you can not connect to a Windows instance due to a previous corruption is to detach the volume from the problem instance, launch a “fix-it” instance of the same OS and same Availability Zone, reattach that volume to the new instance which you can connect to, and then you can modify the old EBS volume as needed to allow access.

The specific error with the old volume that we were dealing with was that a static IP has been assigned, instead of using DHCP. So we needed to get into the registry edit to allow access back to the instance. If you search our internal knowledge base tool for “Enabling DHCP”, it will bring up an article which gives a guide through the process.

After the volume had been edited, it was then ok to detach the volume from the fix it instance, reattach it to the old instance, and start it up to allow for sweet sweet RDP.

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