If you have installed the Fall 2017 Creators Update for Windows 10 and you sync OneDrive files to an external drive, you may be unable to open your OneDrive files if you move the external drive to a computer running an operating system older than Fall 2017 Creators Update for Windows 10.
You may receive an error: “The file cannot be accessed by the system."
The following workarounds are available:
Sign in to onedrive.com with the account that you're having trouble with and download your files.
Tip: To get to your OneDrive online from your desktop, you can also right-click the OneDrive icon in the Notification area, and select View online.
Create a new sync connection on the computer running the older version of Windows. Read how to Set up your computer to sync your OneDrive for Business files in Office 365.
Use a computer running the Fall 2017 Creators Update for Windows 10 (or newer) to open the content.
To sync your OneDrive to an external drive, you need to select a location that is formatted as NTFS. View how to Convert a FAT or FAT32 drive to NTFS.