How to Repair System Files Using System File Checker (SFC)

System File Checker (SFC) is a tool built into Windows that scans all protected system files and replaces damaged or incorrect versions with correct ones. Microsoft notes that when critical system files are missing or damaged, Windows may begin to malfunction, for example with features that stop working, system errors or freezes. Microsoft now says to run a second built-in tool, DISM, before SFC. The steps are the same in Windows 11 and Windows 10.

1. Open Command Prompt as Administrator

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Both tools need administrator rights, so you must be signed in with an account in the Administrators group.

1. Select Start and type cmd.
2. Right-click Command Prompt in the results and select Run as administrator.
3. Select Yes if Windows asks for permission.

Expected result: a Command Prompt window opens with Administrator in its title bar.

2. Run DISM First

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DISM (Deployment Image Servicing and Management) runs a more extensive check than SFC and can repair problems in the Windows component store. It gets replacement files from Windows Update, so stay connected to the internet.

1. Type this command and press Enter:
   DISM.exe /Online /Cleanup-image /Restorehealth
2. Wait for it to finish. Microsoft says this can take several minutes.

If Windows Update itself is broken, DISM can use another repair source, such as Windows installation media, with the /Source option. For example: DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows /LimitAccess, replacing the path with your own source. /LimitAccess stops DISM from also using Windows Update.

Expected result: DISM reports that the operation completed successfully.

3. Run SFC /scannow

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1. In the same window, type this command and press Enter:
   sfc /scannow
2. Leave the window open until the verification reaches 100%. SFC replaces any damaged files it finds with a cached copy.

Expected result: SFC finishes and shows one of the messages in the next section.

4. What the SFC Result Means

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• "Windows Resource Protection did not find any integrity violations." Your system files aren't missing or damaged. Nothing more to do here.
• "Windows Resource Protection found corrupt files and successfully repaired them." Microsoft says the operation was successful. See section 5 if you want the details.
• "Windows Resource Protection found corrupt files but was unable to fix some of them." Use the log in section 5 to find which files, then try section 7.
• "Windows Resource Protection could not perform the requested operation." Run SFC again in safe mode (section 6).

5. See Which Files SFC Repaired

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SFC writes its details to the CBS.log file in %windir%\Logs\CBS. To copy just the SFC entries to a text file on your desktop, run this in an administrator Command Prompt:

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

Open sfcdetails.txt from your desktop. It includes every SFC run on the PC, so check the dates and times to find your latest scan and any files it couldn't repair.

Expected result: you have a list of the files SFC repaired or couldn't repair.

6. Run SFC in Safe Mode If It Can't Complete

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If SFC says it could not perform the requested operation, start Windows in safe mode, which loads only the minimum drivers and services, and run it again.

1. Select Start > Settings > System > Recovery, and next to Advanced startup select Restart now. On Windows 10, it's Settings > Update & Security > Recovery.
2. Select Troubleshoot > Advanced options > Startup Settings > Restart.
3. When the list appears, press 4 or F4 to start in safe mode.
4. Open Command Prompt as administrator and run sfc /scannow again.

Microsoft also suggests checking that the PendingDeletes and PendingRenames folders exist under %WinDir%\WinSxS\Temp.

Expected result: SFC completes and shows one of the other three messages.

7. Replace a File SFC Can't Fix

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This is for experienced users. You need a known good copy of the same file, ideally from another PC running the same version of Windows. In an administrator Command Prompt:

1. Take ownership of the damaged file: takeown /f <path and file name>
2. Give administrators full access to it: icacls <path and file name> /grant administrators:F
3. Copy the good file over it: copy <source file> <destination>

Expected result: running sfc /scannow again no longer lists that file.

Still Not Working? What to Try Next

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• Check without repairing: sfc /verifyonly scans all protected files without changing anything, which is handy for a second opinion.
• Check the Windows image: Dism /Online /Cleanup-Image /ScanHealth scans for damage, and Dism /Online /Cleanup-Image /CheckHealth reports whether the image is healthy, repairable or non-repairable.
• Check the drive: chkdsk C: /f finds and fixes file system errors. Because Windows is using drive C, it offers to run at the next restart.
• Use a recovery option: if files still can't be repaired, Microsoft says you may need to reinstall Windows and points to its recovery options, such as a system restore point or Reset this PC.