How to Run SFC /Scannow in Windows 10, 11 (Stepwise Guide)

About sfc /scannow command

The SFC (System File Checker) command is a powerful Command Prompt tool in Windows used to verify and replace important Windows system files. By running this command, users can ensure the integrity of their operating system files. There are several specific switches available in the SFC command, such as /scannow, which scans all protected system files and repairs any issues it detects. Other switches include /verifyonly, which only scans files without making repairs, and /scanfile, which allows users to scan a specific file for integrity issues.

• Sfc /scannow: scans the integrity of all protected system files and repairs files with problems when possible.

• Sfc /verifyonly: scans the integrity of all protected system files without repairing.

• Sfc /scanfile=: scans the integrity of the referenced file and repairs file if problems are identified.

• …

Among all the command switches, sfc /scannow is the most frequently used one. It is extremely useful to repair incorrect, corrupted, changed, or damaged system files. Then, how do you perform sfc /scannow repair exactly?

How to use sfc /scannow in Windows 10/11 to repair corrupted system files

To run sfc /scannow in Windows 10/11, you can follow the steps below:

👉 SFC scan on Windows 👉 Offline SFC scan 👉 Bonus tip: auto backup Windows 10/11 for system recovery💡

SFC scan on Windows

1. Tap the Search button on the taskbar and type “cmd” in the search box. Right-click “cmd” and then select “Run as administrator”.

2. Type DISM.exe /Online /Cleanup-image /Restorehealth and press Enter. It may take several minutes for the command operation to be completed.

Note: Running the DISM (Deployment Image Servicing and Management) tool prior to SFC is only necessary on Windows 11/10/8.1/8. To run sfc /scannow in Windows 7, you can skip to Step 3.

3. Type sfc /scannow and press Enter to scan system files and replace corrupted files with a cached copy that is located in a compressed folder at %WinDir%\System32\dllcache.

Note: The %WinDir% placeholder represents the Windows operating system folder. For example, C:\Windows.

4. After the verification reaches 100%, you may receive one of the following messages:

▶ Windows Resource Protection did not find any integrity violations. >> A good thing. ▶ Windows Resource Protection found corrupt files and successfully repaired them.  >> A good thing. ▶ Windows Resource Protection found corrupt files but was unable to fix some of them. >> In this case, you can view details of the System File Checker process in %WinDir%\Logs\CBS\CBS.log, and then manually replace the corrupted file with a known good copy of the file. ▶ Windows Resource Protection could not perform the requested operation. >> In this condition, you can perform the System File Checker scan in safe mode, and make sure that the PendingDeletes and PendingRenames folders exist under %WinDir%\WinSxS\Temp.

5. Type exit and press Enter to exit Command Prompt.

Offline SFC scan

If your PC fails to boot, you may perform an SFC scan offline. Here’s how to do it.

1. Boot your PC with Windows installation media or a recovery drive.

2. Open Command Prompt from Windows Recovery Environment.

• For Windows installation media, click Repair your computer > Troubleshoot > Advanced options > Command Prompt.
• For a recovery USB, click Troubleshoot > Advanced options > Command Prompt.

3. In the Command Prompt window, type sfc /scannow /offbootdir=c:\ /offwindir=c:\windows and press Enter.System File Checker utility checks the integrity of Windows system files and repairs them if required.

Note: You need to replace C: with the drive letter of the partition that contains your Windows installation.

4. After the process is complete, reboot your computer.

To learn more about the SFC command on Windows Server, please refer to inaccess boot device on Windows Server 2019.

Although you can fix corrupted system files with the sfc /scannow command, problems may occur during the process, such as sfc /scannow not working, sfc /scannow stuck, etc. You even need to reinstall Windows to repair damaged system files when sfc /scannow fails.

💡Bonus tip: auto backup Windows 10/11 for system recovery

To be released from the heavy work of reinstalling Windows when sfc /scannow fails, you should backup Windows regularly. Compared with reinstalling Windows and all the applications, restoring a system from the backup is much easier. Here I’d like to recommend the best free backup software—AOMEI Backupper Standard.

Step 1. Download, install, and launch AOMEI Backupper. Click on “Backup” and select “System Backup”.

Step 2. The required system partition(s) is (are) selected by default. Choose the destination path to store the backup files. You can save the system image to the local disk, external hard drive, or network location.

Step 3. Click “Schedule Backup” in the left bottom, and then set the frequency of the system backup to run.

Step 4. Confirm the operation and click “Start Backup” > “Add the schedule and start backup now” to run your first backup.

>> Options: you can enable email notification, choose the compression level for the backup image file and select intelligent sector backup or sector-by-sector backup. >> Backup Scheme: it will automatically remove older backups to save disk space for you. This feature is available in AOMEI Backupper Professional and higher editions.

How long will it take to make SFC scannow?

Typically, the SFC process takes only 5-10 minutes, though it might take a bit longer if the task is more extensive. If the process takes over an hour, it could indicate that SFC is stuck.

The SFC /scannow command may get stuck at the start of a system scan or during validation, often showing numbers like SFC /scannow stuck at 4%, 30%, 73%, or even 100%.

Don't worry. In the following content, we will also provide several effective solutions to fix SFC /scannow issues.

Quick fixes for SFC scannow stuck

Run SFC Scan in Safe Mode

If Windows Resource Protection detects corrupted files but can't repair them, causing the SFC /scannow command to get stuck, try running SFC in Safe Mode. Here's a simple guide:

• Press Windows+R to open the Run window and type msconfig.
• Open System Configuration, go to the Boot tab and check Safe Boot.
• Restart your computer to enter Safe Mode.

Your computer will now boot in Safe Mode. Once in Safe Mode, run the SFC scan again to see if the issue is resolved.

Repair SFC stuck with CHKDSK command

If data corruption on the disk is causing the SFC/scannow to get stuck, you can try using CHKDSK to scan and fix the hard disk. Running CHKDSK can identify and repair file system errors, which might resolve the issue. Simply open Command Prompt as an administrator and enter chkdsk /f /r to initiate the scan and repair process.

• Open Command Prompt as an administrator.
• Type chkdsk /f and press Enter.
• When prompted to check the partition during the next restart, type Y and press Enter.
• Restart your computer and check if the SFC issue is resolved.

Use System Restore

A system restore point allows you to revert your computer to a previous state, undoing recent system changes. If you have created a restore point in the past, you can use it to fix issues when the SFC/scannow validation fails. Follow these steps:

• Search for "System Restore" on your computer and open the tool.
• Choose a restore point, either the latest one or another from the list, and click "Next" to proceed.
• Follow the on-screen instructions to complete the restore process.
• After the system restore is complete, open CMD and run the SFC /scannow command again.

FAQs about SFC scannow on Windows 10

1. What is the difference between SFC and DISM?

SFC (System File Checker) scans and repairs Windows system files. Use SFC when you encounter program crashes or missing DLL errors. DISM (Deployment Imaging Service and Management Tool) is more powerful and repairs corrupt files in the Windows system image. Use DISM when SFC cannot repair files.

2. How often should I run DISM?

The DISM and SFC commands help find and repair corrupted files on Windows. Run these commands when you encounter error messages or notice your computer slowing down. For preventive maintenance, running them once a month is a good practice. For more details, refer to this link.

3. Should I run sfc or DISM first?

It's generally recommended to run "sfc /scannow" first before using the DISM (Deployment Image Servicing and Management) tool. SFC focuses on repairing system files, while DISM is more powerful, and capable of repairing the Windows image and servicing the underlying Windows installation. 

4. Is it safe to use sfc scannow?

Yes, it's safe to use the sfc scannow command in most cases. It's a built-in Windows utility designed to repair corrupted system files without causing harm to your system. However, it's always a good idea to create a backup of your important files before running any system repair utilities, just to be safe. 

5. How do I check the integrity of Windows system files?

Open Command Prompt with administrative privileges by searching for "Command Prompt" in the Start menu, right-clicking it, and selecting "Run as administrator." Then, type "sfc /scannow" (without quotes) and press Enter. The tool will scan your system for corrupted or missing system files and attempt to repair them automatically. 

6. Should you run DISM after SFC?

You typically don't need to run the DISM command. However, if the SFC command fails or can't replace a corrupted file, running the DISM command can help fix the underlying system issues, allowing SFC to work correctly. For Windows 7, use the System Update Readiness Tool instead.

Verdict

Now you know how to use sfc /scannow in Windows 10, and 11 to repair corrupted system files. To get prepared for the possible sfc /scannow failure, you should backup Windows regularly with AOMEI Backupper. In addition to backing up the system, AOMEI Backupper can help you sync local folders with Synology NAS.

If you are looking for portable sync software that enables you to sync files on any computer, pick the AOMEI Backupper Technician or Technician Plus edition. Try it now to discover more!