SFC /SCANNOW Command - System File Checker

How to Repair Windows 7 System Files with System File Checker​

   Information

The sfc /scannow command (System File Checker) scans the integrity of all protected Windows 7 system files and replaces incorrect corrupted, changed/modified, or damaged versions with the correct versions if possible.

   Tip

If you get the Windows Resource Protection Could Not Start the Repair Service error when trying to run SFC, then make sure that the Windows Modules Installer service is enabled, click on Start, and set to Manual.

Services - Start or Disable

OR

Copy and paste the command below in the elevated command prompt, and press Enter. After the Windows Modules Installer service has started, try running the SFC command again

net start trustedinstaller

   Note

The KB3022345, KB3035583, and KB3068708 updates will cause SFC to give you a false mismatch message in SFC for files related to these updates.

You can safely ignore these results in your SFC details since it will not affect SFC from being able to repair other system files.

   Warning

Be aware that if you have modified your system files as in theming explorer/system files, running sfc /scannow will revert the system files such as explorer.exe back to it's default state. Make the appropriate backups of your system files that you have modified for theming if you wish to save them before running sfc /scannow.

:note: For the updated Windows 10 tutorial, please see - SFC Command - Run in Windows 10 - Windows 10 Tutorials

CONTENTS:

• Option One: To Run the SFC /SCANNOW Command at Boot
• Option Two: To Run the SFC /SCANNOW Command in Windows 7
• Option Three: How to See and Read Only the "SFC" Scan Results from the CBS.LOG

OPTION ONE

To Run the SFC /SCANNOW Command at Boot

1. For how, see METHOD TWO at this link: SFC /SCANNOW : Run in Command Prompt at Boot

   Note

Using OPTION TWO below is recommended if able.

If you would like to get help with your SFC issue, then be sure to upload and attach your sfcdetails.txt file from OPTION THREE below in your post.

OPTION TWO

To Run the SFC /SCANNOW Command in Windows 7

1. Open an elevated command prompt or an elevated PowerShell, and do step 2 or 3 below for what type of scan you would like to run.


2. To Scan and Repair System Files
NOTE: Scans the integrity of all protected system files and repairs the system files if needed. Please see red WARNING box at the top of this tutorial.
A) In the elevated command prompt, type sfc /scannow, press Enter, and go to step 4 below. (see screenshot below)
NOTE: This may take a little bit to finish.


3. To Only Verify if the System Files are Corrupted
NOTE: Scans and only verifies the integrity of all proteced system files only. This command will not change your system files as in the red WARNING box at the top of this tutorial.
A) In the elevated command prompt, type sfc /verifyonly, press Enter, and go to step 4 below.
4. When the scan is complete, hopefully you will see all is ok like the screenshot below.

   Note

• If SFC could not fix something, then run the command again to see if it may be able to the next time. Sometimes it may take running the sfc /scannow command 3 or more times to completely fix everything that it's able to.
• If not, then download and run the 32-bit (x86) or 64-bit (x64) System Update Readiness Tool for your same installed 32-bit or 64-bit Windows 7, restart the PC afterwards, and try the sfc /scannow command again.
• If still not, then try using OPTION ONE above to run the sfc /scannow command at boot.
• If still not, then you can attempt to run a System Restore using a restore point dated before the bad file occured to fix it. You may need to repeat doing a System Restore until you find a older restore point that may work.
• If still not, then you can use the steps in the TIP box in the OPTION THREE section below to manually replace the files that SFC could not fix if there are not to many fix.
• If there are to many files to manually fix, or you prefer not to use OPTION THREE below, then you could do a repair install without losing anything.

If you would like to get help with your SFC issue, then be sure to upload and attach your sfcdetails.txt file from OPTION THREE below in your post.

5. When done, close the elevated command prompt.

OPTION THREE

How to See and Read Only the "SFC" Scan Results from the CBS.LOG

   Note

When SFC runs, it logs it's actions into the C:\Windows\Logs\CBS\CBS.log. The steps in this option will show you how to see only the specific SFC entries with the [SR] tags in this CBS.log. This can be helpful to show you what files SFC could not fix automatically if you wanted to try and manually replace them.

1. Open an "elevated command prompt" (right click -> Run as administrator).

2. In the elevated command prompt, copy and paste the command below, and press Enter. (See screenshot below)
NOTE: This will place a sfcdetails.txt file on your desktop with only the SFC scan result details from the CBS.LOG in it.

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt"

3. Close the elevated command prompt.

4. Open the sfcdetails.txt file on your desktop to see the SFC scan details in the CBS.LOG.

5. You can safely delete the sfcdetails.txt file afterwards if you like.

   Tip

If you need to replace a corrupted system file that SFC cannot fix, then this will show you how to by extracting a new copy directly from your Windows 7 installation DVD.

Extract Files from Windows 7 Installation DVD

That's it,
Shawn

Related Tutorials

---

• How to Run the System File Checker in a Command Prompt at Boot
• How to Do a System Restore in Windows 7
• How to Do a Repair Install to Fix Windows 7
• How to Run Disk Check in Windows 7
• How to See Windows 7 Reliability and Problem History with Reliability Monitor
• How to Extract Files from the Windows 7 Installation DVD
• How to Troubleshoot a Problem by Performing a Clean Startup in Windows 7 or Vista

 

[csedcooper]

Brink:

Thanks. I figured the solution might be somewhat time consuming.
I went ahead and purchased Microsoft Assure one year service plan.
They fixed remotely. It was worth it.

 

[Brink]

 

[nyrangerslmb]

Noob needs help with scan results

Got the CBS log, it's 2.3MB so it's divided into 3 parts, now what? I'm new to all this but have some computer experience. Here's a quick recap of what led me here.
About a month or two ago I noticed during startup that my raid volume was degraded. Everything seemed to be running fine so I didn't think much of it (I now believe that was a big mistake!). Then in the last few weeks things got strange. I would get "insufficient access...." when trying to uninstall a program, I would sometimes need administrator rights when I'm the only user and then when I tried to correct it wouldn't let me, I would click on start, and then right click computer and couldn't open device manager. I ran a chckdsk but nothing. I then thought it might be spyware, malware and or virus so I ran a Norton Scan, Malwarebytes, Microsoft Safety Scan, Rogue Killer and Norton Power Eraser and still nothing. Only thing I could figure was corrupted disk or OS. Which brings me here. By the looks of the scan I think I'm screwed. I have new disks on the way as well as an external backup. I really don't want to do a clean install and would much rather fix this and clone with Acronis onto the new drives. Can I extract and copy all the Windows/System 32 files to fix this? Any help and advise would be greatly appreciated.

 

[Brink]

Hello nyrangerslmb, and welcome to Seven Forums.

Please go ahead and use Option Three to create a sfcdetails.txt file to upload instead. This way it'll only include the SFC details and be much smaller.

 

[nyrangerslmb]

Thanks, wish it were under better circumstances.

 

[Brink]

It says that it cannot repair the files below. You had one other file it found, but it was able to fix it. If you haven't already, check to see if doing what's in the blue note box at the end of Option Two may be able to allow SFC to repair it afterwards.

• dllhost.exe for Microsoft-Windows-COM-Surrogate

 

[nyrangerslmb]

Does the System Update Readiness Tool take 15-20 minutes to install? It's about 95% done and hasn't moved.

 

[Brink]

Yeah, it can take a bit. If you still have hard drive activity, then it'll be best to let it sit and finish.

 

[nyrangerslmb]

Nothing has worked, I've extracted the file to desktop and when I try to copy it to my folder I get Destination Folder access denied. I try to change the settings in security tab but it won't let me, all the boxes are opaque.

 

[Brink]

If you like, you could do a repair install that should fix it.

http://www.sevenforums.com/tutorials/3413-repair-install.html

 

[nyrangerslmb]

Tried got the following message:

The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue.

• 
  [*] Your current version of Windows is more recent than the version you are trying to upgrade to. Windows cannot complete the upgrade.
  
  

Upgrading Windows will affect the following devices and/or programs:

• These devices might not work properly after the upgrade. Before upgrading, we recommend updating the drivers for these devices. Cancel the upgrade, open Control Panel and search for "update device drivers", or go to the device manufacturer's website to search for updated drivers.

• • 
    [*] Storage controllers: AD4BML2X IDE Controller

• These programs might not work properly after the upgrade. We recommend uninstalling these programs before upgrading. Cancel the upgrade, open Control Panel, and search for "uninstall a program". (Note: Programs marked as * can be safely reinstalled after the upgrade.)

• • 
    [*] iTunes (Please deauthorize computer prior to upgrade)

 

[Brink]

It basically means that your current installation is a newer version than the installation media you are using to do the repair install with. That won't work. The installation media needs to be the same or newer version as what's currently installed.

 

[nyrangerslmb]

It's the same so I don't understand. I tried a sfc scan from bootup with DVD but that was unsuccessful as well. I refused to give up last night and finally was able to replace the corrupted file into sys32 folder. I had to copy the file out of the extraction folder on desktop onto the desktop and then into the windows/sys32 folder. For the heck of it I ran another sfc/scannow and it came up with the same problem. I just replaced the file again and I'm in the process of doing another scan. I'll let you know the outcome.

 

[Brink]

Windows Updates would make your current installation newer.

 

[nyrangerslmb]

So I again extracted and copied the corrupted file and ran a sfc scan and the same corrupted file error was on the sfc details report. So I extracted again copied again did a restart and ran the sfc scan and got the same error. I really hate to uninstall and reinstall all 346 windows update so I can do an upgrade (that would be my last resort to a clean install) is there any other way to replace the dllhost.exe?
Just found the dllhost.exe is in the syswow64 folder also, should I replace that one as well?

 

[Brink]

I wouldn't recommend to uninstall all the updates. That would most likely cause more issues.

If you're not having any issues anymore, then I wouldn't worry about it. Otherwise, it may be time for a clean install.

 

[nyrangerslmb]

Yeah, I was trying to avoid the inevitable, but I think once I get the new hard drives I'll start with a clean install. Will keep a copy of the clean install externally as well as backing up MUCH MORE FREQUENTLY!

Thanks for all your help, even though we couldn't get it resolved, I greatly appreciate all your efforts!!!

 

[shawie60]

Empty txt (CBS.LOG) file ?

actually tried this earlier using the method described and ( i've done it a number of times) and the text file is always empty. So I'm open to suggestions as to why etc or how to cure it ...

 

[Brink]

Hello Shawie,

If you are running SFC at boot, it will not be logged. It only gets logged if you run SFC in Windows.

Are you running SFC at boot or in Windows?

 

[shawie60]

tried both online (in windows) and offline. Even though there is information in the original file the saved text on the desktop is empty. So I've no idea where to go from here tbh ... if i delete the original file cbs.log will it create a new one once another scan has been run?