Windows 11 is one of Microsoft’s most advanced and stable operating systems, but even the best systems can sometimes run into issues. Over time, your computer may experience problems such as missing system files, crashes, or corrupted settings due to software conflicts, improper shutdowns, or malware infections. Fortunately, Microsoft provides built-in repair tools that help fix these issues automatically. One of the most powerful of these tools is the System File Checker (SFC) utility.
The SFC /scannow command is used to scan and repair corrupted or missing system files in Windows 11. It ensures that your operating system runs smoothly by replacing damaged files with clean versions from the Windows component store. In this guide, we’ll explain what SFC is, how it works, and how you can run it using different methods. We’ll also cover what to do if SFC doesn’t fix your issue.
What Is the SFC /Scannow Command?
SFC stands for System File Checker, a Windows tool designed to automatically detect and repair missing or corrupted system files. It verifies the integrity of all protected system files and replaces incorrect versions with the correct Microsoft versions.
The /scannow parameter tells Windows to run a full scan immediately on your PC. This process checks every protected system file, ensuring they are the correct versions.
Here’s what the SFC tool does:
- Scans all protected system files for corruption or modification.
- Restores damaged files using a backup stored in the Windows Component Store (WinSxS folder).
- Prevents system instability and crashes by ensuring that core files are intact.
The SFC /scannow command is especially helpful when your Windows 11 computer behaves abnormally — like apps crashing, the Start Menu not opening, or Windows Update failing.
When Should You Run SFC /Scannow?
You should run SFC /scannow whenever your Windows 11 system starts showing strange behavior, or if you suspect system file corruption. Some common signs include:
- Windows features not working correctly (e.g., File Explorer not responding).
- Frequent system crashes or blue screen errors.
- Missing or corrupted DLL files.
- Windows Update failing to install properly.
- Performance slowdowns or random freezes.
- Error messages mentioning missing or corrupt files.
Running SFC doesn’t harm your system — it’s a safe command that only repairs corrupted files. Therefore, it’s a good troubleshooting step before reinstalling Windows or performing a factory reset.
You can also use SFC after removing malware, performing major Windows updates, or restoring your system from a backup. In many cases, a simple SFC /scannow scan can fix the problem without needing complex repairs.
Before You Run SFC /Scannow
Before you start scanning your computer, it’s essential to prepare your system to avoid interruptions:
- Close all open programs to prevent conflicts during the scan.
- Save your work because your PC might restart automatically.
- Run as Administrator — SFC requires administrative privileges.
- Ensure stable power if you’re on a laptop.
It’s also a good idea to run DISM (Deployment Image Servicing and Management) before using SFC, as it can fix the component store that SFC relies on. We’ll explain how to use both tools together later in this guide.
How to Run SFC /Scannow in Windows 11
Here are the detailed steps to run the System File Checker in Windows 11:
Method 1: Run SFC /Scannow via Command Prompt
Open Command Prompt as Administrator
- Click the Start menu and type “cmd”.
- Right-click Command Prompt and choose Run as Administrator.
Enter the SFC Command
- Type the following command and press Enter:
sfc /scannow
Wait for the Scan to Complete
- The process may take 10–20 minutes, depending on your system speed.
- Do not close the Command Prompt window during the scan.
Check the Results
Once the scan finishes, you’ll see one of these messages:
- Windows Resource Protection did not find any integrity violations.
→ Your system files are fine. - Windows Resource Protection found corrupt files and successfully repaired them.
→ The issues were fixed. - Windows Resource Protection found corrupt files but was unable to fix some of them.
→ You’ll need to run DISM before rerunning SFC (explained below).
Restart Your Computer
- After the process completes, restart your PC to apply the repairs.
Method 2: Run SFC /Scannow in Windows PowerShell
If you prefer PowerShell, follow these steps:
- Right-click the Start button and select Windows Terminal (Admin).
- Type the same command:
sfc /scannow - Press Enter and wait for the scan to finish.
- Review the results just as with Command Prompt.
PowerShell and Command Prompt perform the same function for SFC, so you can use whichever you’re more comfortable with.
Method 3: Run SFC /Scannow in Safe Mode
If your system can’t boot normally or SFC fails in standard mode, try running it in Safe Mode.
Boot into Safe Mode
- Go to Settings → System → Recovery → Advanced startup → Restart now.
- After restarting, select Troubleshoot → Advanced options → Startup Settings → Restart.
- Press 4 or F4 to start in Safe Mode.
Open Command Prompt (Admin) and type: sfc /scannow
Wait for the scan to complete, then restart your system.
Running SFC in Safe Mode ensures that minimal background processes interfere with the repair process.
Using DISM Before Running SFC
If SFC /scannow cannot repair some files, the DISM tool can help. DISM (Deployment Image Servicing and Management) repairs the Windows image that SFC uses to replace corrupted files.
Here’s how to use it:
- Open Command Prompt as Administrator.
- Type the following commands one by one and press Enter after each:
DISM /Online /Cleanup-Image /CheckHealth DISM /Online /Cleanup-Image /ScanHealth DISM /Online /Cleanup-Image /RestoreHealth - Wait for the process to finish. It may take 15–30 minutes.
- After completion, restart your computer.
- Now, run the SFC /scannow command again.
DISM repairs the internal system image, ensuring SFC has access to clean copies of corrupted files. Together, these tools can fix most system issues without reinstalling Windows.
Interpreting SFC Results
After running SFC /scannow, you’ll see one of the following messages:
| Result Message | Meaning |
|---|---|
| Windows Resource Protection did not find any integrity violations. | Your system files are intact; no corruption detected. |
| Windows Resource Protection found corrupt files and successfully repaired them. | Some corrupted files were found and fixed automatically. |
| Windows Resource Protection found corrupt files but was unable to fix some of them. | SFC found issues it couldn’t fix. Run DISM and try again. |
| Windows Resource Protection could not perform the requested operation. | The scan couldn’t complete; try running it in Safe Mode. |
You can also view detailed logs in this file:
C:\Windows\Logs\CBS\CBS.log
Open it with Notepad to see which files were repaired or skipped.
Alternative Ways to Run SFC
If your Windows 11 system fails to boot or has severe issues, you can run SFC from other environments:
1. Run SFC Using Windows Recovery Environment (WinRE)
- Boot your computer and interrupt startup 3 times to launch Automatic Repair.
- Go to Troubleshoot → Advanced options → Command Prompt.
- Identify your system drive using:
dir C:\ - Then run:
sfc /scannow /offbootdir=C:\ /offwindir=C:\WindowsThis command scans offline Windows installations.
2. Run SFC via Installation Media
If your PC can’t start, use a Windows 11 USB installation media:
- Boot from the USB drive.
- Choose Repair your computer → Troubleshoot → Command Prompt.
- Run the SFC command with the same parameters as above.
This allows you to fix corrupted system files even when your computer won’t boot.
Tips to Ensure a Successful SFC Scan
To make sure SFC /scannow runs smoothly:
- Run as Administrator — without admin rights, the tool won’t work.
- Ensure Stable Power — interruptions can cause partial repairs.
- Avoid Running Multiple Repairs Simultaneously — don’t use DISM or updates while SFC is active.
- Wait Patiently — depending on your drive speed, it can take 10–30 minutes.
- Run DISM First if SFC fails to fix issues.
- Reboot After Completion — it helps Windows apply the repaired files correctly.
For persistent problems, repeat the scan two or three times or consider performing a System Restore to a previous stable state.
Why SFC Is Important for Windows 11 Maintenance
SFC plays a critical role in keeping Windows 11 stable and error-free. Every time system files are damaged, they can cause system instability, application errors, and crashes. By using SFC regularly, you can prevent major issues before they escalate.
It’s especially useful for:
- Detecting corrupted files after power failures.
- Fixing post-update issues.
- Cleaning up after malware removal.
- Repairing accidental file deletions or system modifications.
Think of SFC as your computer’s self-healing tool that ensures core system files remain untouched and unaltered. When combined with tools like DISM and Windows Update Troubleshooter, it provides a strong defense against system-level corruption.
Common Errors While Running SFC
Sometimes, users face problems while running the SFC command. Here are common errors and solutions:
| Error | Possible Cause | Solution |
|---|---|---|
| Windows Resource Protection could not start the repair service. | Windows Modules Installer service disabled. | Run services.msc, find Windows Modules Installer, and set Startup Type to Manual. Then rerun SFC. |
| SFC cannot perform the requested operation. | Corruption in WinSxS or running environment. | Run DISM /RestoreHealth, then rerun SFC. |
| SFC stops at a specific percentage. | System interruption or third-party interference. | Run in Safe Mode or Clean Boot. |
| Access Denied error. | Not running as Administrator. | Right-click Command Prompt → Run as Administrator. |
If nothing works, performing a System Restore or using Windows Repair Installation (In-place upgrade) is the last resort.
Conclusion
Running SFC /scannow in Windows 11 is one of the simplest yet most powerful ways to fix many system-related issues without reinstalling Windows. Whether your computer is crashing, performing slowly, or acting unpredictably, this built-in tool can often identify and repair the cause.
Always start with SFC, then use DISM if further repair is needed. These tools ensure your system files stay intact and your PC runs smoothly. Regularly running an SFC scan can also serve as preventive maintenance, helping keep your Windows 11 installation healthy and stable.
Frequently Asked Questions (FAQs)
1. How long does SFC /scannow take to complete?
Usually, it takes 10 to 30 minutes, depending on your computer’s speed and the level of corruption.
2. Can I use my computer while SFC is running?
It’s recommended not to use your PC during the scan to avoid conflicts or incomplete repairs.
3. What should I do if SFC cannot repair some files?
Run the DISM /RestoreHealth command, then try SFC /scannow again. This often fixes unresolved issues.
4. Is SFC /scannow safe to use?
Yes, it’s completely safe. It only repairs or replaces system files with correct versions from Microsoft’s repository.
