Through the looking glass: Microsoft intentionally rolls out updates slowly to monitor feedback. Situations like this highlight the benefit of doing so as only a tiny fraction of the Windows 10 install base was impacted by the bug. Had the update reached everyone at once, Microsoft would have had a much bigger mess on its hands.

Microsoft last week paused the rollout of Windows 10 October 2018 Update (version 1809) due to reports that it was deleting user data. Fortunately, the rollout was in a very early stage as only those that had manually checked for updates had received it. Better yet, Microsoft said reports of actual data loss were limited to one one-hundredth of one percent of version 1809 installs.

After a full investigation, Microsoft managed to fix all known issues in the update and conducted internal validation. Now, the update is being re-released to the Windows Insider community.

John Cable, director of program management, Windows servicing and delivery, said Microsoft will study the results, feedback and diagnostic data from Insiders before taking further steps to re-release the update to other users.

Cable said the issue was related to Known Folder Redirection (KFR). Specifically, the update introduced code that removed empty, duplicate known folders. Combined with another change to the update construction sequence, the update was deleting the original "old" folder locations and their content.

Microsoft identified three specific issues and has implemented fixes for each in the revised update.

Now, the "original" old folder location and its contents should remain intact.

Those still experiencing issues are encouraged to reach out to Microsoft Support ASAP and limit their use of the affected device. Microsoft said it cannot guarantee the outcome of any file recovery work but there are procedures in place that should help users recover lost files.

Microsoft has also added the ability for Windows Insiders to provide feedback regarding the impact and severity of future issues. This, Microsoft said, will allow them to better monitor the most impactful issues, even when feedback volume isn't high.