How to Use SFC Scannow to Repair Windows System Files

If your Windows 11 computer is crashing randomly, showing weird errors, or behaving sluggishly for no reason, there’s a good chance that some system files have become corrupted or gone missing. Thankfully, Windows includes a powerful built-in tool called System File Checker (SFC) that can detect and automatically repair damaged or missing system files.

In this guide, we’ll explain what the SFC command does, when to use it, and how to run it properly on Windows 11 (and 10).

What Is SFC Scannow?

The System File Checker (SFC) is a command-line tool included with all modern versions of Windows. It scans your operating system for corrupt or missing files and restores them using the cached copies stored by Windows.

When you run the sfc /scannow command, Windows performs a full integrity check of your system files and automatically replaces any that are damaged or missing.

You can use it to fix common issues such as:

• Windows not booting correctly
• Broken or missing DLL files
• Crashing apps or unexpected Blue Screen errors
• Windows features not working as expected

How to Use SFC Scannow to Repair Windows 11 System Files

Follow these steps carefully to run the SFC tool and repair your Windows system:

Step 1: Open Command Prompt as Administrator

1. Press Windows + S, type cmd or Command Prompt in the search box.
2. Right-click on Command Prompt and select Run as administrator.
3. Click Yes when prompted by User Account Control (UAC).

You should now see an elevated Command Prompt window that says Administrator in the title bar.

Step 2: Run the SFC Scannow Command

Once the Command Prompt is open, type the following command and press Enter:

sfc /scannow

This will start a system-wide scan for corrupted or missing files. Depending on your system speed and storage, the process may take anywhere from 10 to 30 minutes.

Tip: Don’t close the Command Prompt window or interrupt the scan while it’s running — doing so may cause incomplete repairs.

Step 3: Wait for the Scan to Complete

When the scan finishes, you’ll see one of the following messages:

• Windows Resource Protection did not find any integrity violations.
  (Your system files are healthy — no repair needed.)
• Windows Resource Protection found corrupt files and successfully repaired them.
  (Corrupted files were found and automatically fixed.)
• Windows Resource Protection found corrupt files but was unable to fix some of them.
  (Some files couldn’t be repaired — you may need to use the DISM tool.)

Step 4: Run DISM Tool If SFC Can’t Repair Files

If the SFC scan fails or can’t fix all corrupted files, try using the DISM (Deployment Image Servicing and Management) tool before re-running the SFC command.

1. In the same Command Prompt (Admin) window, type the following command and press Enter: DISM /Online /Cleanup-Image /RestoreHealth
2. Wait for the process to finish. This can take 10–20 minutes depending on your system speed.
3. Once done, restart your PC.
4. Open Command Prompt (Admin) again and run: sfc /scannow

This time, SFC should be able to repair the remaining corrupted files.

How to Run SFC in Safe Mode

If the SFC scan keeps failing in normal mode, you can run it in Safe Mode, where only essential Windows components load.

To boot into Safe Mode:

1. Press Windows + I to open Settings.
2. Go to System → Recovery → Advanced startup → Restart now.
3. After the system restarts, choose Troubleshoot → Advanced options → Startup Settings → Restart.
4. Press 4 to boot into Safe Mode.
5. Once in Safe Mode, open Command Prompt (Admin) and run: sfc /scannow

This often works when third-party software interferes with normal SFC operations.

How to View SFC Scan Results

You can view detailed SFC logs to see which files were repaired or couldn’t be fixed:

1. Press Windows + R, type: %windir%\Logs\CBS\ and press Enter.
2. Open the file named CBS.log with Notepad.
3. Look for lines containing the word corrupt or repair.

You can also extract the relevant details by running this command in Command Prompt:

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

This will save a summary report called SFC_Details.txt on your Desktop.

Conclusion

The SFC Scannow command is one of the most reliable tools in Windows 11 for repairing corrupt system files and restoring stability. It’s simple to run, doesn’t require third-party software, and can often save you from having to reinstall Windows entirely.

If the SFC command doesn’t solve your problem on the first try, running DISM /RestoreHealth before another scan usually does the trick. With these two built-in tools, you can keep your Windows system running smoothly and error-free.