While there are plenty of different things you can do with the command, sfc /scannow is the most common way that the sfc command is used. Sfc /scannow will inspect all of the important Windows files on your computer, including Windows DLL files. If System File Checker finds a problem with any of these protected files, it will replace it.
How to Use SFC /Scannow
How to Interpret the CBS.log File
Every time you run System File Checker, a LOG file is created that itemizes every file that was checked and every repair operation that completed. System File Checker will now verify the integrity of every protected operating system file on your computer. It might take a while to finish. When the verification process completes, you’ll see something like this in the Command Prompt window, assuming problems were found and corrected: …or something like this, if no problems were found: Assuming Windows is installed on the C: drive then the log file can be found here and opened with Notepad or some other text editor: This file could be useful for advanced troubleshooting or as a resource for a tech support person that might be helping you out.
Executing SFC /SCANNOW From Outside of Windows
When running sfc /scannow from outside of Windows, like from the Command Prompt available when you boot from your Windows installation disc or flash drive, or from your System Repair Disc or Recovery Drive, you’ll have to tell the sfc command exactly where Windows exists. Here’s an example: The /offbootdir= option specifies the drive letter, while the /offwindir= option specifies the Windows path, again including the drive letter. Depending on how your computer is configured, the Command Prompt, when used from outside of Windows, doesn’t always assign drive letters in the same way that you see them from inside Windows. In other words, Windows might be at C:\Windows when you’re using it, but D:\Windows from the Command Prompt in ASO or SRO. In most installations of Windows 11, Windows 10, Windows 8, and Windows 7, C: usually becomes D: and in Windows Vista, C: is usually still C:. To check for sure, look for the drive with the Users folder on it—that will be the drive Windows is installed on, unless you have multiple installations of Windows on multiple drives. Browse for folders in Command Prompt with the dir command.
