What caused the Data Loss problem for those who installed Windows 10 v1809

Windows 10 v1809 October 2018 Update was hit by the worst bug till now. A lot of users who upgraded to it reported a loss of files from their user folder. It turned out to be a bug in Windows 10 Upgrade deleted those files because of what is Microsoft calling Known Folder Redirection (KFR) redirection issue. Microsoft is now rolling out a fixed version with ISO and Media Creation offerings, while those who have already updated to v1809 are getting a Cumulative Update 17763.55 (KB4464330) as part of the fix. Now let’s deep dive into what caused the data loss problem for those who installed Windows 10 v1809.

What caused the Data Loss in Windows 10 v1809

Known Folder Redirection is a technique which allows one to change the default location of folders like Downloads, Music, Documents, OneDrive, etc. to somewhere else on the PC without changing where they appear on the Windows Explorer.

When v1809 was under testing, a couple of users reported that when this technique was used, they had an extra copy of empty folder at those default location. Microsoft added a new set of code in the October 2018 Update to remove these empty, duplicate known folders. This changed combined with another change to the update sequence, resulted in the deletion of the original “old” folder locations and their content, leaving only the new “active” folder intact.

Known Folder Redirection

What is even surprising to note is that this was a remote issue which was reported by a set of users while this version was with Insiders. Since Feedback Hub is based out of voting, this major issue was buried as it did not get many votes from all the users. Shared by @WithinRafael on Twitter, it’s pretty clear that Microsoft had it overlooked. IMO any issues which are around file deletion must be taken seriously.

Data Loss problem in Insiders

Windows Team adds further that the user files were deleted in the following situations:

  1. If the contents of c:\users\username\documents were not moved to D:\documents when the location was being changed,  then a user could also encounter this issue.
  2. When the user chose to redirect their folders to another folder on OneDrive but chose not to move existing files to new location. Since those files were not moved, October Update treated them as duplicate folders and deleted them.
  3. If Known Folder redirection was used using an early version of the OneDrive client with settings to turn on the Autosave feature. The client didn’t move the old files to the new location.

So if the files were left in the old location they where removed by the Update. Now here is what I am surprised at. Why did users choose to leave the files after migration to a new location? Secondly, why were they looking at these folders when they had already migrated to a new location?

On a related note – comments like these should cause concern to Microsoft:

The Win 10 updates are unpredictable. I’m scared to death each time the automatic updates (which I can not disable) happen. After an update one of more installed software stop working and need re-installing. I have no viruses or cracked software. The last Win 10 update corrupted the MBR (Master Boot Record) on my 2 laptops and 1 desktop. 3 computers done the same update at the same time and having corrupted MBRs is NOT a coincidence. Microsoft owes $900 just for this damage alone. i spent $300 for each computer to have the drives removed and put new drives in so I can keep my data that was not corrupted in the old hard drives. The “reset Win 10” without losing personal data function in the advanced settings was not working on all 3 computers. Thank God I had 3 spare SSDs as a backup, but it is such a hassle going through the old hard drives and saving all the data in different locations. I’m switching to MAC and ditching everything PC related – PERIOD!

If you lost your data files, you can try and recover those files.

Windows 10 v1809 October 2018 Update is now available for download again. If you wish to still play safe, you may defer the installation of this feature update.

Posted by on , in Category Windows with Tags
Ashish is a veteran Windows, and Xbox user who excels in writing tips, tricks, and features on it to improve your day to day experience with your devices.


  1. Mike Steel

    After installing 17763.55 to HP ELiteDesk 800 G3 1809 -> blue screen. WDF_VIOLATION.

    And according to here this happens on (all?) HP desktops…


    I contacted MS support about this and this is what they said:

    Agent: Actually HP computers are not the only product affected for this issue other computers as well like DELL etc. That’s why for now, we’ve temporarily paused the update for people who seek to check for updates, to investigate an isolated reported issue and will make it available for download again once ready.

    Me: Ok, so this is known issue for 17763.55 cumulative update?

    Agent: That’s correct and other issue has been reported as well but our higher level of support already working on it.

  2. M Rankin

    no problem on my HP

  3. “If you lost your data files, you can try and recover those files.” This is not needed. All users files and folders are in the Windows.old folder after the upgrade. This happens after every major Windows Update. All KFR and usual locations are copied with all of the other Windows files to the Windows.old folder which is a backup in case you need to restore the previous version you had before the update.

  4. This problem was due to the Intel chipset. The issue has now been fixed and being tested in insider builds and the full release should be imminent. All other reported issues with the last 1809 update, such as missing files and folders has also been fixed.

  5. Zac Stannett

    In recovery screen
    See Advanced recovery options -> troubleshoot -> command prompt
    Command : ren C:WindowsSystem32driversHpqKbFiltr.sys HpqKbFiltr.sys_old

    some tips:
    – re check if you are on the correct drive.
    For example my prompt start default in X:windowssystem32
    In this folder there is also a folder called “drivers” but doesn’t contain the file hpqkbfiltr.sys
    c: (without ) and after that
    cd c:windowssystem32drivers
    dir /p
    than i can find the file HpqKbFiltr.sys

    next run the command
    ren HpqKbFiltr.sys HpqKbFiltr.sys_old

    – last tip: the folder “Driver” with uppercase D does not exist.
    a folder drivers with lowercase d does exist.

    hopefully this could be helpful.

  6. Nope, not in this case of KFR (see other reports).

  7. Rocky45

    One funny thing that got my attention from that user’s comment in the article: “I’m switching to MAC and ditching everything PC related”
    Isn’t a MAC technically considered a Personal Computer?

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