How to Use the SFC /Scannow Command to Repair Windows

Last Updated on April 25, 2026

If your Windows computer is suddenly freezing, randomly crashing with Blue Screens of Death (BSOD), or built-in apps like the Edge browser refuse to open, you likely have corrupted system files. A sudden power outage, a failed Windows update, or a lingering malware infection can easily scramble the core files Windows needs to function.

The Crucial First Step: Run the DISM Command

In the old days of Windows XP and Windows 7, you could just run the SFC command by itself. However, on Windows 10 and Windows 11, the System File Checker relies on a hidden backup folder (called the Windows Component Store) to grab healthy copies of broken files.

If that backup folder is also corrupted, the SFC scan will fail. Therefore, modern IT professionals always run the Deployment Image Servicing and Management (DISM) tool first to ensure the backup cache is healthy.

1. Click your Windows Start button and type cmd into the search bar.
2. Right-click on Command Prompt and select Run as administrator. (This will not work if you skip this step).
3. Click Yes on the User Account Control prompt.
4. In the black window, type the following command exactly as written and press Enter:

DISM.exe /Online /Cleanup-image /Restorehealth

The tool will connect to the internet, download replacement files directly from Microsoft’s servers, and fix your local backup cache. This usually takes about five to ten minutes. Once the progress bar hits 100 percent, you are ready to run the actual SFC scan.

Before you panic and completely reinstall your operating system, there is a built-in diagnostic repair tool you need to run. It is called the System File Checker (SFC).

SFC acts as an automated mechanic for your hard drive. It scans every single protected operating system file, verifies its digital integrity, and automatically replaces any missing or damaged files with a healthy copy. A clean SFC result can instantly rule out core operating system damage, saving you hours of troubleshooting time. Here is exactly how to run it properly on modern Windows machines.

How to Run the SFC /Scannow Command

Now that your system image is repaired, you can confidently run the System File Checker.

1. In that same elevated, Administrator Command Prompt window, type the following command and press Enter:

sfc /scannow

1. The utility will immediately begin the verification phase of the system scan.
2. Do not close the black Command Prompt window until the verification reaches 100 percent. Depending on the speed of your processor and hard drive, this can take anywhere from a few minutes to half an hour.

How to Read Your SFC Scan Results

Once the scan finishes, Windows will print one of four messages on your screen. Here is what they mean and what you should do next:

“Windows Resource Protection did not find any integrity violations.”
This is the best-case scenario. It means all of your core Windows files are perfectly healthy. If your computer is still crashing, you now know the issue is hardware-related or caused by a third-party app, not Windows itself.

“Windows Resource Protection found corrupt files and successfully repaired them.”
The tool did its job! It found broken files and replaced them using the cache we repaired earlier with DISM. Restart your computer and see if your glitches are gone.

“Windows Resource Protection found corrupt files but was unable to fix some of them.”
This means the tool found a broken file but it was actively being used by Windows and couldn’t be overwritten. To fix this, you will need to reboot your computer into Safe Mode and run the sfc /scannow command again while the system is locked down.

“Windows Resource Protection could not perform the requested operation.”
An antivirus program or a severe hard drive error is blocking the scan. Try running the scan in Safe Mode. If it still fails, your hard drive may be physically failing.

It may ask you for your Windows media if it needs any files off of it so keep it handy.