When installing a lot of Windows updates, or a few very large updates (such as a service pack or KB2919355), the updates may fail and the system may revert the changes. If that happens, check the Windows Update history (Windows Update → View update history), and view the details of the failed updates.



If the error code is 0x800F0922, verify whether there's still enough free disk space available on the system drive (C:-drive). If the volume is almost full, there may be enough to download updates, but not enough to actually install them. Aside of the downloaded packages, the unpacking and installation of updates, additional space is needed for system restore points and the old versions  ...