Use SFC scannow command to fix Windows 10 system file errors

If you notice that your computer frequently crashes or has problems during startup... then the cause is most likely due to Windows system files being corrupted, lost, or even changed when you installed a program or software on your computer.

While Windows 10 does a pretty good job of protecting the system files your computer needs to function properly, including application files, drivers, and even Windows Updates, errors can still occur in some cases.

Just like previous versions of Windows, Windows 10 also comes with a built-in System File Checker (SFC). This utility will scan, verify, and repair any corrupted files on your system.

1. How to use SFC /scannow on Windows 10

1. Press Windows + X to open the Power User Menu and select Command Prompt (Admin). This is because you must run the SFC command as an Admin.

2. On the Command Prompt window, type the command below and press Enter:

sfc /scannow

3. Once the scan is complete, you will see one of the following messages on the screen:

• Windows Resource Protection did not find any integrity violations : There are no missing or corrupted files on your system.

• Windows Resource Protection could not perform the requested operation : If this message appears, it means that there was a problem during the scanning process and an offline scan is required.

• Windows Resource Protection found corrupt files and successfully repaired them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log : You will receive this message if SFC was able to fix the problem you encountered. You can now navigate to or view the details.

• Windows Resource Protection found corrupt files but was unable to fix some of them: In this case you have to fix the corrupted files manually.

2. Run SFC /Scannow on other drives

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

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

3. View SFC scan details

To view the details of a System File Checker stored in the CBS.Log file, you must copy a readable copy to the Desktop:

1. Press Windows + X key combination to open Power User Menu and select Command Prompt.

2. On the Command Prompt window, type the command below and press Enter:

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfclogs.txt"

3. Open sfclogs.txt on Desktop with Notepad. This file will contain all the details of the scanned system files and information about the files that could not be repaired.

Note : SFC scan details are only available when you scan in Windows, not available when you scan offline in Command prompt.

If you must know what SFC files cannot be repaired, use the Find function in the text application with the phrase ”cannot repair”. You can also use “repair” and “repaired” to see any files that have been repaired.

Use “corrupt” to detect corruption in various applications. If the file cannot be easily repaired, then you need to replace and remove it. This is shown in the final status message: “Windows Resource Protection found corrupt files but was unable to fix some of them” .

4. Run SFC scan in Safe Mode

If you see the second status message during the system scan: “Windows Resource Protection could not perform the requested operation” then the SFC scan must be performed in Safe Mode. To access it, select “Change advanced startup options” from the Start menu.

Select “Restart now” to start Windows 10 in Safe Mode .

A blue screen will appear. Using your keyboard arrow keys, select Troubleshoot > Advanced options , which will lead to the next screen below.

Select “Command Prompt” from the available options.

Sign in with your Windows user ID and password. It's best to use the Enter key to quickly navigate these screens.

Now the Command Prompt screen appears on a blue background in Safe Mode. You can scan your system much faster here and the verification and status alerts don't take long.

5. Scan and repair system files on Windows 10 Offline

1. Press Windows + I key combination to open Settings application.

2. On the Settings interface, click Update & security.

3. Next click Recovery.

4. Under Advanced startup , click Restart now.

5. Click Troubleshoot.

6. Click to select Advanced options.

7. Click Command Prompt to boot your computer using only Command Prompt.

8. During reboot you will be prompted to enter username and password to continue.

9. Whenever you need to run SFC outside of Windows, you must tell the utility exactly where the Windows installation files are located.

On the Command Prompt window, enter the command line below so that the utility can understand the location of the Windows and System Reserved partition:

wmic logicaldisk get deviceid, volumename, description

10. Enter the following command into the Command Prompt window and press Enter:

sfc /scannow /offbootdir=C:\ /offwindir=D:\Windows

Note:

In the treen command, use /offboodir to switch the specific drive letter of the System Reserved partition, in this case C, and /offwindir to switch the specific location of Windows files, in this case D:\Windows.

11. After the scan is complete, close the Command Prompt window.

12. Click Continue to exit and return to Windows 10.

6. Repair system files on Windows 10 manually

If System File Checker cannot fix one or more errors, you will have to repair these files manually.

Open the sfclogs.txt file to see which files are corrupted, search for the location of the files and follow the steps below:

1. Press Windows + X key combination to open Power User Menu, then select Command Prompt (Admin).

2. On the Command Prompt window, type the command below and press Enter:

takeown /f C:\Path-and-File-Name

Note:

Replace C:\Path-and-File-Name with the path and name of the corrupted file. For example, C:\Windows\System32\appraiser.dll.

3. Allow access to the corrupted files under Admin rights by entering the following command into Command Prompt and pressing Enter:

icacls C:\Path-and-File-Name /Grant Administrators:F

4. Replace the files in the section asked by copying the command below and pressing Enter:

copy C:\Path-SOURCE-and-File-Name C:\Path-DESTINATION-and-File-Name

Note:

In the above command replace C:\Path-SOURCE-and-File-Name with the good path and file name, and replace C:\Path-DESTINATION-and-File-Name with the destination path and name of the corrupted files.

For example:

copy D:\Files\appraiser.dll C:\Windows\System32\appraiser.dll

5. Type Yes and press Enter to confirm overwrite.

After replacing the files, you can type the command SFC /verifyonly into the Command Prompt window and press Enter to check the integrity of all files and check which files are corrupted to fix.

Additionally, if you just want to fix some files, you can check the integrity of each file using the command:

sfc /VERIFYFILE=C:\Path-and-File-Name

For example:

sfc /VERIFYFILE=C:\Windows\System32\kernel32.dll

See more articles below:

• Your Windows 10 PC's Internet Connection Is Slow, Here's How to Fix It
• Enable Credential Guard to enhance Windows 10 security
• Clear Windows 10 update cache to free up memory space

Good luck!