What does the message "AWS instance scheduled for retirement" mean?

This message is usually related to hardware maintenance by Amazon. It can be resolved by stopping and starting your server, which will move it to different hardware and fix the problem. It is highly recommended to create a backup before stopping the server to ensure you can recover your data if something goes wrong in the process.

IMPORTANT: Note that you should not "restart" the server but instead separately "stop" and "start" it or perform a "hard reboot", since a normal reboot would not change the hardware.