Description of System File Checker (Sfc.exe)
This article describes System File Checker (Sfc.exe), which is a command-line utility used with the Windows File Protection (WFP) feature.
Applies to: Windows 10 - all editions, Windows Server 2012 R2
Original KB number: 310747
System File Checker gives an administrator the ability to scan all protected files to verify their versions. If System File Checker discovers that a protected file has been overwritten, it retrieves the correct version of the file from the cache folder (
%Systemroot%\System32\Dllcache) or the Windows installation source files, and then replaces the incorrect file. System File Checker also checks and repopulates the cache folder. You must be logged on as an administrator or as a member of the Administrators group to run System File Checker. If the cache folder becomes damaged or unusable, you can use the
sfc /scannow, the
sfc /scanonce, or the
sfc /scanboot commands to repair its contents.
System File Checker tool syntax
Sfc [/Scannow] [/Scanonce] [/Scanboot] [/Revert] [/Purgecache] [/Cachesize=x]
/Scannow: Scans all protected system files immediately and replaces incorrect versions with correct Microsoft versions. This command may require access to the Windows installation source files.
/Scanonce: Scans all protected system files one time when you restart your computer. This command may require access to the Windows installation source files when you restart the computer. The SfcScan DWORD value is set to 2 in the following registry key when you run this command:
/Scanboot: Scans all protected system files every time you start your computer. This command may require access to the Windows installation source files every time you start your computer. The SfcScan DWORD value is set to 1 in the following registry key when you run this command:
/Revert: Returns scan to the default setting (do not scan protected files when you start the computer). The default cache size is not reset when you run this command. This command is equivalent to the
/Enableswitch in Windows 2000.
/Purgecache: Purges the file cache and scans all protected system files immediately. This command may require access to the Windows installation source files.
/Cachesize=x: Sets the file cache size to x megabytes (MB). The default size of the cache is 50 MB. This command requires you to restart the computer, and then run the
/purgecachecommand to adjust the size of the on-disk cache. This command sets the SfcQuota DWORD value to x in the following registry key:
For more information about the Windows File Protection feature, see Description of the Windows File Protection feature.
If you need assistance from Microsoft support, we recommend you collect the information by following the steps mentioned in Gather information by using TSS for deployment-related issues.