The update is testing Microsoft's fix for their File Deletion Bug, which addresses the issue of Microsoft deleting the original folders they believed were empty after the location of the Known Folder (such as My Documents) was moved.
Microsoft has corrected issues that caused data loss on systems upgraded to the company's new feature update the October 2018 Update.
Some users really did lose files, which happened when they upgraded to Windows 10 version 1809, also known as the "October 2018 Update".
In a blog post, the company says the number of customers impacted by the bug was small, with "reports of data loss" limited to "one one-hundredth of one percent of version 1809 installs". This is the feature that lets you move a known folder like C:\Users\Name\Downloads to D:\Downloads, for example.
The bug, Cable wrote, affected people who had used a feature called Known Folder Redirection, a tool for folks who have filled their hard drive and wanted new files destined for their Desktop, Documents, Pictures, Videos, Camera Roll, and other such default directories to be stored on another device, such as in D:\user.
Correcting the issue required three specific fixes, each of which you can read about in more detail in Microsoft's blog post.
Some users told Microsoft that the previous April 2018 major Windows Update created duplicate empty copies of these folders if redirection was enabled.
Unfortunately for some users, "that change, combined with another change to the update construction sequence, resulted in the deletion of the original "old" folder locations and their content, leaving only the new "active" folder intact", Cable said. The company also states it will provide an update as soon as a fixed version of the Windows 10 October 2018 will be rolled out again. If there are still files in the "Documents" folder then you're not affected by the issue, according to another tweet from Sarkar.
He added that Microsoft Support and our retail stores customer service personnel are available at no charge to help customers.
#WindowsInsiders If you've run into the "missing files after update" issue for 1809/October 2018 Fall update, please call our support line.