Again, I'm unaware of any NAS, from any manufacturer, that can create disk images of a separate device, so this is not unusual.
"Backup Plan is ASUSTOR’s free backup software for Windows OS. It can be used to backup data from a Windows PC or Server to specified destination devices including NAS, FTP server, or the local machine. Backup Plan supports one-time backups, scheduled backups and synchronization. If your original data should become damaged, destroyed or lost, Backup Plan also provides a convenient data restoration function."
https://www.asustor.com/en/online/Colle ... ?topic=253Basically ABB can create plans to periodically backup specific files, folders or drives, but not in the way that you're looking for. It can be used to restore lost files, and it will maintain the folder structure. However, it cannot be used to, "recover full operation system to a new HDD," nor can it recover or restore partitions. Typically all you want to backup using ABB (or EZSync) are your user files (documents, pictures, music, videos, etc.), as backing up installed programs or the operating system is pointless - restoring them to a new drive will not work. The errors you're running into are unavoidable, as some programs will always be running.
So what you need is disk imaging software (as I said, free options are perfectly fine), and save a copy of the image to the NAS.