System File Checker

sfc
Developer	Microsoft
Release	June 25, 1998;28 years ago (1998-06-25)
Operating system	Microsoft Windows
Type	System utility
License	Proprietary commercial software
Website	docs.microsoft.com/en-us/windows-server/administration/windows-commands/sfc

System File Checker (SFC) is a utility in Microsoft Windows that allows users to scan for and restore corrupted Windows system files.

sfc /verifyonly (no repair)

If it finds a problem, it will attempt to replace the problematic files from the DLL Cache (%WinDir%\System32\dllcache). If the file is not in the DLL Cache or the DLL Cache is corrupted, the user will be prompted to insert the Windows installation media or provide the network installation path. System File Checker determines the Windows installation source path from the registry values SourcePath and ServicePackSourcePath. It may keep prompting for the installation media even if the user supplies it if these values are not correctly set.

In Windows Vista and onwards, files are protected using access control lists (ACLs), and if it finds a problem, it will attempt to replace the problematic files from the Windows Side-by-side Backup (%WinDir%\WinSxS\Backup). However, the above command has not changed.

System File Checker in Windows Vista and later Windows operating systems can scan specified files. Also, scans can be performed against an offline Windows installation folder to replace corrupt files, in case the Windows installation is not bootable. For performing offline scans, System File Checker must be run from another working installation of Windows Vista or a later operating system or from the Windows setup DVD or a recovery drive which gives access to the Windows Recovery Environment.

In cases where the component store is corrupted, the "System Update Readiness tool" (CheckSUR) can be installed on Windows 7, Windows Vista, Windows Server 2008 R2 or Windows Server 2008, replaced by "Deployment Image Service and Management Tool" (DISM) for Windows 10, Windows 8.1, Windows 8, Windows Server 2012 R2 or Windows Server 2012. This tool checks the store against its own payload and repairs the corruptions that it detects by downloading required files through Windows update.