If you have installed the update KB2821895 , and then run the System File Checker using the command sfc /scannow, the scan reaches 100% complete, and you receive the following error:
Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.log windir\Logs\CBS\CBS.log. For example C:\Windows\Logs\CBS\CBS.log. Note that logging is currently not supported in offline servicing scenarios.
The system file repair changes will take effect after the next reboot.