Windows 10 update KB 3213986 triggers System Restore error 0x80070091


A post early this morning confirms that KB 3213986, the latest cumulative update for the most widely used version of Windows 10, breaks System Restore on some systems.

The error report (see screenshot) on Günter Born’s  says there’s an “unspecified error” while working in a module called AppxStaging.

System Restore, you may recall, relies on Restore Points to save and retrieve copies of system files, settings, registry entries, and the like. It first appeared in Windows ME, became a mainstay of system protection in Windows XP and 7, then was intentionally hidden in 8.1—accessible, but only if you knew where it was buried. In Windows 10, automatic creation of Restore Points is turned off by default, but many people (present company included) recommend turning them on as one of the first steps after installing a new copy of Windows 10.

With System Restore working properly, recovering from a bad patch or a faulty program can be a three- or four-click process. However, the System Restore feature has fallen out of favor, with Microsoft making it much simpler to reset a PC by copying over all system files.


My testing shows that:

  • It is update KB 3213986 that causes the problem to occur in the first instance.
  • Rolling back the update does not correct the problem.
  • Performing the known fix returns System Restore functionality.
  • For how long, we don’t yet know.

Born confirms this finding and gives a of the “known fix,” which involves five steps and culminates in cleaning out a protected folder that’s owned by the Win10 system ID TrustedInstaller. Going through those steps is not for the faint of heart. As Born says:

As a Windows 10 user, you are forced to use a third-party backup tool (Macrium Reflect, EaseUS ToDo Backup, etc.) to create system backups on a periodical base, in the hope that you are able to restore a damaged OS.

You have to wonder whether Microsoft even tests these things.