Everything You Need to Know About SFC/Scannow

The System File Checker (SFC) is a useful command-line utility to scan and repair protected system files in Windows. It's the easiest and fastest technique to assess the integrity of your computer, detect problems with installations and updates, and find replacements for missing or corrupted files where possible.

Here we cover all you need to know about this versatile utility to ensure that you stay on top of any PC problems.

Running a Basic SFC Scan

To run the System File Checker (SFC), you need to run the command line in Administrator mode, which can be selected from the Start menu. It's a very easy-to-remember command you need to enter to begin the basic system scan.


The SFC command runs equally well on Windows 10 as well as Windows 8.1, 8 and even 7. No matter which Windows operating system you have, you should keep it updated for best results.

Sfc Scannow Verification Stage

The system scan process will take some time to complete, which can take several minutes, so you have to be patient. You can use the computer for other activities in the mean time, as the system scanning does not significantly burden your CPU and other resources.

Sfc Scannow No Integrity Violations

Once the verification phase of a system scan is done, you will receive one of the following status messages:

  • Windows Resource Protection did not find any integrity violations: there are no missing or corrupted system files, and no further action is needed.
  • Windows Resource Protection could not perform the requested operation: this problem can be resolved by running SFC scan in safe mode (see last step). Also, check that "PendingDeletes" and "PendingRenames" folders exist when you type %WinDir%\WinSxS\Temp in Run command. Windows 10 users can also open the Run menu using Win + R.
Sfc Scannow Temp Files
  • Windows Resource Protection found corrupt files and successfully repaired them: the details for such repaired files are included in CBS.Log, which has been covered below.
  • Windows Resource Protection found corrupt files but was unable to fix some of them: according to Microsoft, such files need to be manually repaired.

Running SFC/Scannow on Other Drives

SFC/Scannow can be also used to check and repair non-system files in other drives, such as D: or an external hard drive, USB drive, SD card, or other storage media. To run the scan on such drives, you need to slightly modify the command as shown below. The rest of the procedure is the same as above.

sfc/scannow/offbootdir=Drive Name: /offwindir=Drive name:\windows
Sfc Scannow External Drive

How to See and Analyze SFC Scan Log Files

Each time you run an SFC scan, the process will generate a log file named "CBS," which can be viewed in the Windows folder of C: drive under the Logs sub-folder.

Sfc Scannow Cbs Logfile

The best way to open the log file is to use Notepad or any other text editor. Wordpad and Word are the best applications for this purpose, as they allow easily searching for relevant text and are easier to scroll down.

Sfc Scannow Cbs Logfile Open Wordpad

If you only have to know what SFC files cannot repair, use the Find function in the text application like "cannot repair." You can also use "repair" and "repaired" to view any files that have been repaired.

Sfc Scannow Cbs Ctrl F

Use "corrupt" to detect corruption in various applications. If the file cannot be repaired easily, then you need to replace and remove it. This is shown in the last status message: "Windows Resource Protection found corrupt files but was unable to fix some of them." The entire detailed procedure has been covered here.

Sfc Scannow Cbs Ctrl F Corrupt

Running SFC Scan in Safe Mode

If you see the second status message in a system scan: "Windows Resource Protection could not perform the reques'ted operation," then the SFC scan has to be performed in safe mode. To access it, select "change advanced startup options" from the Start menu.

Sfc Scannow Change Advanced Startup

Select "Restart now" to boot Windows 10 in safe mode.

Sfc Scannow Advanced Startup

A blue screen will emerge. Using the keyboard's arrow keys, select "Troubleshoot" followed by "Advanced options," which will lead to the next screen below.

Sfc Scannow Safemode Troubleshoot

Select "Command Prompt" from the available options.

Sfc Scannow Command Prompt

Log in using your Windows user ID and password. It is better to use the Enter key to quickly navigate these screens.

Sfc Scannow Command Prompt Safe Mode

Now the command prompt screen is visible against a blue backdrop in safe mode. You can run a much faster system scan here, and the verification and status alerts don't take much time.

Sfc Scannow Safe Mode Operation

We have explored different ways to access SFC file settings in Windows 10. Running an SFC scan alerts you to the presence of corrupted applications, such as missing DLL files in the boot menu, although there are better ways to handle such files.

How often do you use SFC/Scannow in regular usage? Which are the major applications that work coherently with this system scanner? Please let us know in the comments.

Sayak Boral

Sayak Boral is a technology writer with over eleven years of experience working in different industries including semiconductors, IoT, enterprise IT, telecommunications OSS/BSS, and network security. He has been writing for MakeTechEasier on a wide range of technical topics including Windows, Android, Internet, Hardware Guides, Browsers, Software Tools, and Product Reviews.

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