Ask Leo! by Leo A. Notenboom

What is the System File Checker, and how do I run it?

Search First! Then browse: Categories | Full Archive | By Date | Newsletter
Ask Leo! on Facebook

Home » Windows » Windows Programs

Summary: The System File Checker is a little known utility that validates that Windows own files are undamaged. It's a simple to run command line program.

What is the System File Checker, and how do I run it?

Windows XP works very hard to maintain the integrity of the system files on your machine. If you try to replace one of the "protected" files, you may get an informative message that the operating system has put the old approved version back. Not all files are under system file protection and even for those that are, there are ways around it. Occasionally system files become corrupt.

Enter the SFC, the System File Checker.

SFC is a good utility to run when you suspect that system files have been somehow corrupted. It validates the digital signatures of all of the Windows system files and restores any that it finds are incorrect. It will use the on-disk cache if possible, but SFC may require that you provide your original installation CD or a location with an image thereof. (See this prior article about not having an installation CD on some of the alternatives if that's the case.)

To run the system file checker press Start, Run, and then type in SFC, followed by its options.

"Enter the SFC, the System File Checker."

The most common usage of SFC is this:

SFC /scannow

This causes SFC to scan your system immediately. SFC can take a few minutes to run. As I said above, have your installation CD or equivalent available in case SFC needs to replace a damaged file.

While it's not documented anywhere, if SFC replaces any system files, I'd reboot. I just like to make absolutely certain that the file replacement actually takes effect.

The Microsoft knowledgebase includes more detailed SFC documentation, including more options to check at boot time, control the size of the system file protection cache, and so on. Speaking of which, the knowledgebase also includes System File Protection documentation, covering the mechanism Windows XP uses to keep your system files safe automatically.

UPDATE: If you have no CD, but you do have an I386 directory or CD image somewhere, check out this article: How do I tell Windows where my I386 folder has moved? Once you make the changes therein, you should be able to run SFC to completion.

Article C1896 - February 28, 2004

Was this article helpful? «Yes» «No»

Recent Comments
120 Comments

how do i run sfc if system file is crupt

Posted by: Ritesh Gupta at July 12, 2010 11:04 AM

hi, i can not open my internet explorer,what can i do?

Depends entirely on what happens when you try and your OS version. Are you up to date? Scanned for malware with up to date scans? Not nearly enough info for me.
Leo
20-Jul-2010

Posted by: sepideh at July 19, 2010 4:27 AM

I often run the SFC utility and I do have the OEM version of my O/S on CD ! I put the CD in my DVD/CD drive and tap the shift key to prevent the CD from auto run ,once the light stops flickering on the drive showing the system is trying to run the CD ,then I type SCF /scannow (note the space between the F & /) It takes about 20 miniutes to run and I have very high cvonfidence in this utility
Nick

Posted by: Nick at July 30, 2010 7:25 AM

how can we recover the .nk2 file

Posted by: Abdul at August 4, 2010 1:44 AM

I have tried running SFC but it asked for CD & then said it couldn't proceed as the operating system on the CD was older than the one on the computer. How can that be and what can I do about it please?

Posted by: Kanga at August 13, 2010 7:45 AM

Post a comment on "What is the System File Checker, and how do I run it?":



(Name will be included when your comment is published.)



(Email Address will not be published.)

Remember Me?

By popular demand...
my tip jar
Cuppa Joe
Buy Leo a Latte!

(you may use HTML tags for style)

RSS feed Subscribe to the RSS Feed specifically for comments on this article.

Before commenting, please...

  • Read the article at the top of this page. If your comment shows you didn't, it'll be deleted and ignored.

  • Comment only on this article. Use the Google search box at the top of the page if you have a question about something else.

  • Don't include personal information in the comment. No email addresses. No phone numbers. No physical addresses.

  • Don't spam. Excessive links to unrelated sites within a comment or across multiple comments will cause all such comments to be removed.

  • Don't ask me to recover lost passwords or hacked accounts. I can't, and those comments will be deleted.

  • I can't respond to every comment. And I can't vouch for the accuracy of others who do.

Please wait. Your comment is being processed ...


Question? Ask Leo!