I have encountered an issue when creating custom AMIs (images) on EC2 instances. If I start up a Windows default 2012 server instance with a custom bootstrap/user-data script such as;
PowerShell "(New-Object System.Net.WebClient).DownloadFile('http://download.microsoft.com/download/3/2/2/3224B87F-CFA0-4E70-BDA3-3DE650EFEBA5/vcredist_x64.exe','C:\vcredist_x64.exe')"
It will work as intended and go to the URL and download the file, and store it on the C: Drive.
But if I setup a Windows Server Instance, then create a image from it, and store it as a Custom AMI, then deploy it with the exact same custom user-data script it will not work. But if I go to the instance url (http://169.254.169.254/latest/user-data) it will show the script has imported successfully but has not been executed.
After checking the error logs I have noticed this on a regular occasion:
Failed to fetch instance metadata http://169.254.169.254/latest/user-data with exception The remote server returned an error: (404) Not Found.