Windows Server 2019 Instance created from snapshot to upgrade server

Since you are creating the AMI, it's possible the password generation code is not there or corrupted. You might have saved previous password as well - try using that password. Also, you are simply upgrading RAM. That is, you want to change the instance type. You don't need to go through the process mentioned. All you need to do is shutdown the EC2, change instance type and start the EC2. That's it.

For your scenario, all you need to do is

• stop the EC2
• change instance type
• start EC2

With your process or creating snapshots or AMI, you can troubleshoot using the following methods.

There are several potential reasons why you can't connect to your new Windows Server 2019 instance created from a snapshot. Let me walk you through some troubleshooting steps:

1. Security Group Configuration: Verify that the security group associated with your new instance allows RDP traffic (port 3389) from your IP address. Even if you used the same security group as the original instance, it's worth double-checking.

2. Network Configuration: Ensure that the new instance is in a public subnet with a route to an Internet Gateway, has a public IP address assigned, and that the Network ACLs allow RDP traffic.

3. Password Generation Issue: The fact that the password isn't being generated suggests there might be an issue with the Sysprep process. When creating an instance from a Sysprep snapshot, Windows should go through its initial setup which includes generating a new password.

4. Sysprep Configuration: There might be an issue with the Sysprep configuration files. For Windows Server 2019, check the unattend.xml file at C:\ProgramData\Amazon\EC2-Windows\Launch\Sysprep\Unattend.xml. If there's a profile corruption issue, you might need to change <CopyProfile>true</CopyProfile> to <CopyProfile>false</CopyProfile>.

5. Instance Status Checks: Verify that the instance has passed all status checks in the EC2 console. If it's failing checks, there might be underlying issues with the instance itself.

6. System Logs: Examine the system logs in the EC2 console for any error messages that might indicate what's causing the connection issues.

7. Additional Volumes: Since you mentioned the snapshot includes disk1s that were attached to the original instance, ensure that these additional volumes aren't causing boot or configuration issues.

If the problem persists, you might want to try:

• Creating another instance from the backup snapshot (non-Sysprep) to see if you encounter the same issues
• Stopping and starting the instance, which might resolve some initialization issues
• As a last resort, you may need to create a new instance without using the snapshot and manually migrate your data and applications

Remember that when you create an instance from a snapshot, you're essentially creating a copy of the instance at the point the snapshot was taken, so any configuration issues present at that time will be carried over.
Sources
EC2 instance from Snapshot not accessible | AWS re:Post
Troubleshoot Sysprep issues with Amazon EC2 Windows instances - Amazon Elastic Compute Cloud
Suddenly I can't connect to my ec2 server | AWS re:Post

Hey,

Hope you're keeping well.

You don’t need to create snapshots or run Sysprep just to increase RAM. In EC2, memory is tied to the instance type, so you can simply stop the instance, change the instance type to one with 16 GB (for example t3.xlarge or m5.xlarge), and then start it again. When using a Sysprep’d image, Windows will reset the Administrator account and disable password generation until the EC2Config/EC2Launch service runs correctly, which can prevent RDP access. If you must use that AMI, ensure EC2Launch is installed and configured, and verify the instance has a security group allowing inbound TCP 3389 from your client.

Thanks and regards,
Taz