Lightsail windows 2019 server instance - windows not activated.

If your Lightsail Windows Server 2019 instance is not activated after being created from a snapshot, this is likely due to the Windows KMS activation not properly connecting to the AWS KMS server. This is a known issue that can occur when restoring from snapshots.

To resolve this activation issue, you can try the following steps:

1. Set the AWS KMS target by running this command in Command Prompt (as administrator):

slmgr.vbs /skms 169.254.169.250:1688

2. Then activate Windows by running:

slmgr.vbs /ato

These commands will point your Windows instance to the AWS KMS server (which is available at the special IP address 169.254.169.250) and attempt to activate Windows.

If this doesn't work, the issue might be related to how the snapshot was created. For best results with Windows instances, it's recommended to stop the instance before creating a snapshot to ensure data consistency. Running snapshots on active Windows instances can sometimes result in incomplete or corrupted data.

If you continue to experience issues, you might need to create a new instance directly from the base Windows Server 2019 image rather than from your snapshot, or contact AWS Support for further assistance.
Sources
Troubleshoot Amazon EC2 Windows instance start issues - Amazon Elastic Compute Cloud
Lightsail Windows snapshots attaching as Linux /dev/sda1 — cannot restore Windows instances | AWS re:Post
Troubleshooting license type conversion in License Manager - AWS License Manager

For windows 2019, you can also try this solution here to activate Windows https://repost.aws/knowledge-center/windows-activation-fails