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