Revised update released to Windows Insider test pilots.
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.
A few days ago, Microsoft was force to pause the rollout of Windows 10 version 1809, as upgraders complained that files in their computers' Documents, Pictures and Downloads folders had vanished.
The file deletion issue also saw Microsoft pull Windows Server 2019 downloads.
"We have fully investigated all reports of data loss, identified and fixed all known issues in the update, and conducted internal validation," Microsoft's director of program management for Windows servicing and delivery John Cable said.
Cable said Microsoft found that the file deletion happened if users had enabled redirection of Windows user data folders - including Desktop, Documents, Pictures, Screenshots, Videos, Camera roll and more - away from their default location under C:\Users\$UserName.
Some users told Microsoft that the previous April 2018 major Windows Update created duplicate empty copies of these folders if redirection was enabled.
Microsoft decided to remove these duplicate folders through code incorporated into version 1809.
Unfortunately for some users, "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," Cable said.
Cable also identified another file deletion scenario involving redirection of Known Folders to OneDrive storage whereby contents of the original default directory were erased if they weren't moved.
Furthermore, an early buggy version of the OneDrive client with autosave turned on didn't move files in users Documents and Pictures folders from the old location to the new one.