After upgrading to Windows 10/8/7, it's better to backup Windows.old folder so that you can downgrade to the previous Windows version at anytime.
Upgrading to a new version of Windows, you will have a Windows.old folder on your root directory of C: drive. This folder contains all the data from your old installation of Windows, so it consumes a lot of disk space. You can access this folder in File Explorer and copy files to your new Windows installation, but you cannot delete it there. You may have to use Disk Cleanup to delete Windows.old folder. You can also use it to restore your system to the previous version of Windows if something goes wrong with current Windows system or you just cannot get used to it.
Keep the Windows.old folder, even if you don’t want to restore your old Windows operating system, because you might find out that some files weren’t copied to your new Windows installation using for a couple days. Windows 10 gives you an option “Go back to Windows 7” or “Go back to Windows 8.1” that allows you to easily restore your old system just by clicking it. However, it is wasting a large amount of space while the free space on your system drive is precious. Windows 10 will erase the Windows.old folder to free up disk after 30 days automatically. After a month, you can still use the Windows.old folder to revert to your old system if you keep the Windows.old folder, only in a more complicated way. The best choice is to back up the Windows.old folder to another location, and then delete it to free up space.
AOMEI Backupper Standard is freeware developed to backup file/folder, system, partition, and disk for Windows 10/8.1/8/7. With advanced compression function, it can save much more disk space; with great compatibility, it can backup to any location that Windows detects: with file filter, it can backup folders with file extension; with backup encryption, it can keep your data secured. Learn how to backup folders with Windows backup software AOMEI Backupper.
1. Download, install and launch AOMEI Backupper.
2. Click “Backup” tab, and select “File Backup”.
Tip: If you own an AOMEI account, you can backup Windows.old folder to AOMEI Cloud using the Cloud Backup feature.
3. Select the Windows.old folder to backup.
First of all, click "Add Folder" in the main page of file backup.
Then, click "Computer" and select C:\Windows.old in the local computer.
4. Click where the arrow point to select a location to save the image backup.
5. Click “Start Backup” to run the backup.
This backup software will run the backup in the background, and it won’t disturb you using the computer. If you ever want to use this folder, you can restore the entire folder or restore partial files from the backup. If you have not yet upgraded to Windows 10, you can backup your PC before upgrading to Windows 10 with AOMEI Bcakupper, so you can restore your system in a much easier way.