It's still not safe to install

Windows 10 version 1809 (build 17763.17) with data loss fix releases, but only to testers

Microsoft fixes the bug that caused files to disappear after installing the Windows 10 October 2018 Update, but the fix is only available to testers.

Windows 10 version 1809 (build 17763.17 and build 17763.55)

Microsoft is announcing that the problem regarding users missing files after installing the Windows 10 October 2018 Update (version 1809) have been identified and permanently resolved starting with build 17763.17 (KB4467228).

However, instead of re-releasing the new version to the public, the company is now making the October 2018 Update (build 17763.17) with the fixes only available for testers with devices enrolled in the Slow and Release Preview of the Windows Insider Program.

Once the software maker feels confident that the fixes work as expected, then version 1809 will be available again to the public, but we don’t know when it’s going to happen.

What caused the missing files problem?

Alongside the news, Microsoft is also explains that:

This problem occurred if Known Folder Redirection (KFR) had been previously enabled, but files remain in the original “old” folder location vs. being moved to the new, redirected location.

In previous feedback from the Windows 10 April 2018 Update, users with KFR reported an extra, empty copy of Known Folders on their device. Based on feedback from users, we introduced code in the October 2018 Update to remove these empty, duplicate known folders. 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.

The good news is that Windows 10 build 17763.17 includes the fixes to prevent data loss during the upgrade process. Also, update KB4464330, which is rolling out with the October 2018 Patch Tuesday, contains the fixes for users that already updated to October 2018 Update.

The only caveat is that it appears that the update fixes the problem, but it doesn’t restore the missing files for affected users as the company continues to advice to call the company directly at +1-800-MICROSOFT or take the device to the nearest Microsoft store where affected users will receive help free of charge. However, the company says that “cannot guarantee the outcome of any file recovery work.”

What Microsoft is doing to prevent future problems?

In addition to fixing the problem, helping for affected users, Microsoft says that is updating the Windows Insider Feedback Hub to include a new indicator that testers can use to “provide an indication of impact and severity when filing User Initiated Feedback.” According to the company, ” this will allow [them] to better monitor the most impactful issues even when feedback volume is low.”