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. Now it has re-released the update, fixing the issue while shedding some light on how many people were impacted by the bug. This caused a new issue, though - users with KFR previously enabled found that files still in their default location were deleted, the idea being that only the new "active" redirected folders would remain.
Microsoft claims to have taken care of the inadvertent file deletion issue affecting users upgrading Windows 10, and is rolling out a fixed version to early adopters in its Windows Insider program for further testing.
Microsoft investigated isolated reports of users missing files after updating.
"Prior to re-releasing the October 2018 Update our engineering investigation determined that a very small number of users lost files during the October 2018 Update", stated the Microsoft announcement.
In a blog post, Microsoft said the affected population was low - "one one-hundredth of one percent" of people who installed the update experienced data loss, the company claims.
In April, Windows Insider guinea pigs reported a bug in this folder redirection feature that created empty copies of the so-called known folders - the standard issue directories like Desktop, Downloads, etc.
Additionally, the blog post explains in some technical detail how how the glitch happened, and says that Microsoft will assist anyone who lost their personal files with recovering their data.
This includes fixes for system components such as the Windows kernel, graphics and file systems, the wireless networking and peripherals subsystems, along with the JET database engine, Windows Media Player and the Edge and Internet Explorer web browsers among others.
However, if you're somebody who wants to keep hold of the files they've downloaded for whatever reason, or uses the folder for storage in some way, then obviously this is something you need to be careful around if you're using Disk Cleanup. To make sure to remedy such issues, the Windows Insider team says that it is adding the ability to flag the severity of the feedback that they initiate.
For those who are affected, they should call Microsoft at +1-800-MICROSOFT or find a local number in your area.
The fixed versions of Windows are getting floated in Microsoft's Windows Insider Program, which is a program for software testers.