RDP Internal Error Has Occured

Hello! The issue might be due to the RDP certificate not working after disabling TLS and it might need to be recreated. However, this can be a challenge if you don't have access.

If you use Session Manager, you might be able to connect to the instance via a terminal. For more information on how to set it up, you can read https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager-getting-started.html

If you are unable to set Session Manager (for example, you don't have the SSM Agent installed), you can try using EC2Rescue with a temporary rescue instance. For more information, please follow the steps here https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ec2rw-gui.html#ec2rescue-offline

If this doesn't work and you have a recent backup (like an EBS snapshot or AMI), you might want to try creating a new EBS volume from the snapshot and swapping the current one.

If the issue persists and you have a support contract, I suggest to open a support case so that an engineer can further assist.