According tomedia reports, some users who recently installed Windows 10 updates, including KB4549951, reported that they logged in without loading user profiles that contained all the data, customizations, and documents. Conversely, after the update is complete, Windows 10 launches a mysterious temporary user profile vulnerability that may remove the user’s data and even delete them.
Although the issue has been reported for months, it now appears to be present and may affect all users. It’s not clear why Windows 10 loads a brand new user profile or how it loads.
Many users also reported that their data, including documents or pictures, disappeared after windows 10KB4549951, released on April 14.
After the update is applied, Windows renames the normal user profile folder, and then creates and loads temporary user profiles when the PC starts.
When Windows 10 updates are installed and data, including system customization, magically disappears, the original profile is renamed, but the good news is that most users’ profiles or data are not permanently deleted by this vulnerability.
The original profile should still be in C: users, but the data will be in a file that ends with “.ooo” or “.bak”.
Fortunately, users have a way to get them back — restart Windows at least six to eight times, at which point the user’s profile and data should be returned.
It is not clear exactly how many restarts are needed or whether the restarts apply to everyone. Some users still report that their files have completely disappeared and that they cannot find or recover it.
Some users also reported the issue in Windows 10 version 1909 to 1903.
According to multiple Microsoft support staff, users can also solve the problem by setting up a new account and manually transferring data from the temporary account to the new account.
A more appropriate option would be to back up the files stored on the system drive before installing the update.