How to repair damaged Windows system files using SFC and DISM commands
The System File Checker tool built into Windows can check Windows system files for corruption or other changes. If a file has been modified, it will automatically replace that file with the correct version. Here’s how to use it.
When should you run these commands
If Windows is experiencing blue screen or other crashes, apps are crashing, or some Windows features are not working properly, there are a couple of system tools that may be able to help.
The System File Checker (SFC) tool built into Windows will check Windows system files for corruption or other changes.
If a file has been modified, it will automatically replace that file with the correct version. If the SFC command does not work, you can also try the Deployment Image Servicing and Management (DISM) command in Windows 8, 10 or 11 to repair the basic Windows system image.
On Windows 7 and earlier, Microsoft offers a downloadable “System Update Readiness Tool” instead. Let’s take a look at how to use it.
Run the SFC command to repair system files
Run the SFC command when troubleshooting a buggy Windows system.
SFC works by finding and replacing corrupted, missing, or changed system files. Even if the SFC command does not repair any files, running it will at least confirm that the system files are not corrupted and then you can continue to troubleshoot the system in other ways.
You can use the SFC command as long as the computer itself starts. If Windows will start normally, you can launch it from an administrative command prompt.
If Windows does not start normally, you can try starting it in safe mode or the recovery environment by booting from the installation media or recovery disc.
However, if you get to a command prompt—usually, safe mode, or the recovery environment—you’ll use the command the same way.
Just remember that if you boot Windows normally, you will need to open Command Prompt or PowerShell with administrative privileges. To do this, right-click the Start button and select Command Prompt (Administrator).
Note: In Windows 11, you may need to select “Windows Terminal (Admin)” instead of “Command Prompt (Admin)” or “PowerShell (Admin)”.
At the command prompt, type the following command and hit Enter to perform a full system scan and attempt SFC repairs:
Command Prompt with sfc /scannow running.
Leave the Command Prompt window open for the command to complete, which may take some time. If everything is in order, you will see the message “Windows Resource Protection did not find any integrity violations”.
If you see the message “Windows Resource Protection found corrupt files but could not repair some of them”, try restarting your computer in safe mode and run the command again. And if that fails, you can also try booting with the installation media or recovery disc and try it from there.
Scan results now—corrupt files found.
Run the DISM command to fix SFC issues
You don’t normally have to run a DISM command. However, if the SFC command fails to work correctly or cannot replace a damaged file with the correct one, the DISM command – or the System Update Readiness Tool in Windows 7 – can sometimes repair the Windows platform and make SFC work properly.
To run a DISM command in Windows 8, 10, and 11, open Command Prompt, PowerShell, or Windows Terminal with administrative privileges. Type the following command and press Enter to have DISM check your Windows Component Store for corruption and automatically fix any problems it finds.
Allow the command to finish running before closing the Command Prompt window.
This may take five to ten minutes. It’s normal for the progress bar to stay at 20 percent for a while, so don’t worry about that.
Command Prompt Runs the DISM command.
If the results of the DISM command indicate that nothing has changed, restart your computer and you should then be able to successfully run the SFC command.
On Windows 7 and earlier, the DISM command is not available. Alternatively, you can download and run the System Update Readiness Tool from Microsoft and use it to scan your system for problems and try to fix them.
Note: If you’re still using Windows 7, you’ll need to get the correct version of the Readiness Tool. The latest version available is “System Update Readiness Tool for Windows 7 for x64-based Systems (KB947821) [October 2014].” Download this.
Try a system restore or a system reset afterwards
If you are still experiencing system issues and SFC and DISM commands are not helping you, you can try more drastic measures.
Running the System Restore tool will restore Windows operating system files, settings, and applications to a previous state.
This may fix system corruption issues if the operating system was not also corrupted at the previous point when the restore point was created.