System File Checker is a very useful tool to use when you suspect issues with protected Windows files, like many DLL files.

Sfc Command Availability

The sfc command is available from within the Command Prompt in most Windows operating systems, including Windows 11, Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, and Windows 2000. System File Checker has been part of Windows Resource Protection since Windows Vista, and is sometimes referred to as Windows Resource Checker in those operating systems. In Windows XP and Windows 2000, this tool is part of Windows File Protection.

Sfc Command Syntax

Its basic form, this is the syntax required to execute System File Checker options: sfc options [=full file path] Or, more specifically, this is what it looks like with options: sfc [/scannow] [/verifyonly] [/scanfile=file] [/verifyfile=file] [/offbootdir=boot] [/offwindir=win] [/?]

Scan and Replace All Corrupt Files

In the above example, the System File Checker utility is used to scan and then automatically replace any corrupt or missing system files. The /scannow option is the most commonly used switch for the sfc command. See How to Use SFC /Scannow to Repair Protected Windows Operating System Files for more information on using the command in this way.

Repair a Specific File

The sfc command above is used to scan ieframe.dll and then repair it if an issue is found.

Scan a Different Windows Installation

In the next example, protected Windows files are scanned and repaired if necessary (/scannow) but this is done so with a different installation of Windows (/offwindir=c:\windows) on a different drive (/offbootdir=c:).

Scan Everything, But Don’t Repair

Using the sfc command with the /verifyonly option, System File Checker will scan all protected files and report any issues, but no changes are made.

Sfc Related Commands & More Information

The sfc command is often used with other Command Prompt commands, such as the shutdown command so that you can restart your computer after running System File Checker. If Windows needs a copy of a file to replace the corrupt one with, it’ll get it from C:\Windows\WinSxS\Backup. If that source has been compromised, Windows will access the internet to download the correct files from Microsoft’s website. See Microsoft’s piece on System File Checker for more information you may find useful.