SFC /SCANNOW Command - Run in Windows 8

How to Run "SFC /SCANNOW" Command at Boot or in Windows 8 and 8.1​

   Information

The SFC command scans the integrity of all protected system files and replaces incorrect versions with correct Microsoft versions.

This tutorial will show you how to run the sfc /scannow command at boot or in Windows 8 to attempt to repair corrupted or modified system files.

   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/tap on Start, and set to Manual.

Services - Start, Stop, and Disable in Windows 8

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

If SFC is unable to repair corrupted system files because the store (source) is corrupted, then you could run the Dism /Online /Cleanup-Image /RestoreHealth command to fix Windows component store corruption, then afterwards try running the SFC scan again.

   Warning

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.

CONTENTS:

• Option One: To Run SFC /SCANNOW Command at Boot
• Option Two: To Run SFC /SCANNOW Command in Windows 8
• Option Three: How to View Only the "SFC" Scan Results from the CBS.LOG

OPTION ONE

To Run SFC /SCANNOW Command at Boot

1. Open a command prompt at boot.

2. In the command prompt, type diskpart and press Enter, then type list volume and press Enter. (see screenshot below)



3. Make note of the drive letters for your boot drive (ex: 350MB "System Reserved" partition) and Windows 8 drive, then type Exit and press Enter. (see screenshot above)
NOTE: If you do not have a "System Reserved" partition, and are not multi-booting with another operating system, then the boot drive and Windows 8 drive may be the same drive letter.

4. In the command prompt, type the command below and press Enter. (see screenshot below)
NOTE: You will see a blinking cursor at the prompt until finished. This will take a while to finish running though.


sfc /scannow /offbootdir=C:\ /offwindir=D:\windows

   Note

You will need to substitute the drive letter of the partition/volume where your system boot files are stored in the offbootdir=C: part of the command above instead.[

You will need to substitute the drive letter of your Windows 8 partition/volume in the offwindir=D: part of the command above instead.

5. When the scan is complete, hopefully you will see an all is ok message like below.




6. Close the command prompt, and restart the computer to start Windows 8.

   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 times restarting the PC after each time to completely fix everything that it's able to.

If not, then run the Dism /Online /Cleanup-Image /RestoreHealth command to repair any component store corruption, restart the PC afterwards, and try the sfc /scannow command again.

If still not, then you could do a refresh of Windows 8, or run a System Restore using a restore point dated before the bad system file occured to fix it. You may need to repeat doing a System Restore until you find a older restore point that may work.

When running SFC offline (at boot), SFC logging in the CBS.log file is not supported to be able to create a sfcdetails.txt file in OPTION THREE below.

OPTION TWO

To Run SFC /SCANNOW Command in Windows 8

1. Open an elevated command prompt or elevated PowerShell.

2. In the elevated command prompt or PowerShell, type sfc /scannow and press Enter. (see screenshot below)
NOTE: This may take a while to finish running.



3. When the scan is complete, hopefully you will see an all is ok message like the bottom screenshot below.
NOTE: Luckily SFC was able to repair my corrupted system files automatically.

   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 times restarting the PC after each time to completely fix everything that it's able to.

If not, then run the Dism /Online /Cleanup-Image /RestoreHealth command to repair any component store corruption, 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 could do a refresh of Windows 8, or 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 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 THREE

How to View 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.

When running SFC offline (at boot) in OPTION ONE, SFC logging in the CBS.log file is not supported to be able to create a sfcdetails.txt file.

1. Open an elevated command prompt or elevated PowerShell.


2. In the elevated command prompt or PowerShell, copy and paste the command below and press Enter.
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. When finished, 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:

If you have to many files that are corrupted, then run the Dism /Online /Cleanup-Image /RestoreHealth command to repair any component store corruption, restart the PC afterwards, and try the sfc /scannow command again.

If you only have a few, then you could manually extract a new copy directly from your Windows 8 installation DVD or USB thumb drive, or ISO file if in a virtual machine.

Extract Files from Windows 7 Installation DVD

That's it,
Shawn

Related Tutorials

---

• How to Refresh Windows 8 and 8.1
• How to Reset Windows 8 and 8.1
• How to Use DISM to Fix Component Store Corruption in Windows 8 and Windows Server 2012

 

[Brink]

Im stuck with this. does it mean that its still scanning?

Hello Orion0921, and welcome to Eight Forums.

Correct. It is still scanning.

DISM - Fixing Component Store Corruption in Windows 8

 

[GEP63]

thanks

 

[Brink]

thanks

I'm glad it could help, and welcome to Eight Forums.

 

[KirkH420]

So the At-Boot scan proved to be a lot more work than it appeared to be when I read the above article. Long story short.... no-good.
It looks like it's possible that this technique might not continue to be useful as we move into the future of storage devices. My system is installed on an NMVE SSD and it seems that the System Boot sector is some kind of logic partition stored in the NAND and whatever the controller/driver is that enumerates it, isn't being being loaded during this pre-boot environment. That's just a guess though, I don't actually know what I'm talking about, LOL. When I look at my partitions in AOMIE Partition Assistant, it often shows that there is 1 more partition than will be shown in Windows Partition Manager. I've seen this elusive partition showing up in other 3rd party partition software as well. Anyway, to give a bit more information what actually made this scan impossible: Most of today's computers aren't going to have drive letters assigned to these hidden system partitions. I was able to unhide the 260MB System (it is actually labeled) boot partition, and assign a functional drive letter to it. Windows sees it just fine. Diskpart sees it just fine. However Diskpart in the pre-boot environment is completely unaware of it. Diskpart was also unsuccessful at assigning a drive letter on it's own, it even says somewhere in there that it's impossible to do it (Diskpart help Assign). Oh well, I guess I'll go throw some more rubbish at the wall and see what sticks. I'm trying to figure out what could be causing explorer to randomly hang for a few seconds, as though it's seeking to a mechanical hard disk that's gone to sleep or something. Anyway, thanks for the info.