The only possible solution that has surfaced on the forums so far is to locate and disable a group policy that deletes user profiles when they reach a certain age. This can be done by running the gpedit command in the Windows search bar and navigating to Computer Configuration/Administrative Templates/System/User Profiles and disabling the Delete user profiles older than a specified number of days on system restart feature.
Microsoft has yet to begin pushing the Windows 10 October Update to the public, so the only people experiencing the issue are likely to be those who forced it via Windows Update. Given the circumstances, it'd definitely be wise not to rush the update and wait for guidance from the company itself.
We've reached out to Microsoft and will update this article should we receive a response.