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1000001: Using the System File Checker
Home › Forums › Knowledge Base › 1000001: Using the System File Checker
- This topic has 24 replies, 14 voices, and was last updated 1 year, 11 months ago.
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February 2, 2017 at 5:48 am #83021
woody
Da BossAKB1000001: Using the System File Checker
By @NoelCarboni
Published 2 Feb 2017 rev 1.0
Microsoft provides a self healing feature for Windows called Windows File Protection. It’s been around for a while, actually. Windows File Protection helps keep Windows sane by watching for un-sanctioned changes to system files. A particular program called the System File Checker (SFC) is provided as part of Windows File Protection:
https://blogs.technet.microsoft.com/askcore/2007/12/18/using-system-file-checker-sfc-to-fix-issues/
The short story is that you want to get a little geeky you can use SFC to see if your Windows installation is healthy. It’s quite easy – just start an elevated CMD window and run this command:
SFC /VERIFYONLY
Go ahead and try it. It’ll run for a few minutes – or maybe even a few tens of minutes – and it will thoroughly check all your Windows system files.
Note that just checking your system’s health shouldn’t harm anything. It’s only checking, not changing things. You might even get a warm and fuzzy feeling when SFC says all’s well!
But the all important question is: What do you do if SFC reports an error?
SFC can be asked to try to repair basic problems it finds with the Windows system files using your local servicing database (hey, some of the data in all those gigabytes of Windows installation can actually be useful). Specifically If the above SFC /VERIFY command says there are errors, you can try a next step: Run SFC again but this time with a different switch, where you ask it to actually fix any errors it finds.
Note that if you have been hacking Windows system files yourself, you might have caused the errors yourself and an SFC repair will likely undo those hacks. I personally recommend never doing hacks that change system files and break Windows File Protection. It’s quite possible to run a customized and tuned up Windows 8 system that still passes SFC checks – I do!
This command asks SFC to repair any problems it finds:
SFC /SCANNOW
It might tell you that it found and repaired the errors. If so, that’s great and here comes that warm and fuzzy feeling. You’re all done!
But – unfortunately – there are some errors this command can’t fix. Like any files, the servicing database itself in Windows can become corrupted, making an SFC repair impossible. It can and does happen.
If SFC /SCANNOW informs you that it could not repair errors, you can dig through the file C:\Windows\Logs\CBS\CBS.log to find out why. It’s cryptic and voluminous, but a search for the string “cannot repair” often turns up the key clues. Pay attention to the dates and times as data from multiple runs accumulates in that log file, but persistence pays.
Last month I observed that an uncorrectable error was introduced on my Windows 8.1 system after I installed the December set of “Group A” (everything cumulative) updates:
Specifically, SFC reported (via CBS.log) that the file Sound Recorder.lnk was corrupted and that the corruption couldn’t be repaired because the “source file in the store was also corrupted”.
Fortunately, with Windows 8 and newer there’s a way to escalate the automatic repair process to yet another level – and it really works – using a DISM command. DISM is the Deployment Imaging and Servicing Management tool provided with Windows. Yep, now we’re gettin’ seriously geeky. Just like a crack IT professional.
Specifically, if you find yourself with errors that SFC just can’t repair, clear your schedule for 10 minutes or so and try this command:
DISM /Online /Cleanup-Image /RestoreHealth
It actually goes online to the Windows Update site and does what it can to repair the local servicing database on your running system! After running it, SFC /SCANNOW might actually be able to repair those errors it couldn’t repair before!
You can find more information on Microsoft’s site about DISM:
https://technet.microsoft.com/en-us/library/hh824869.aspx
Once the DISM command is done – which may take quite a while so be patient – go back and try the SFC /SCANNOW command again. There’s a good chance it will now succeed and you might actually get back to that warm feeling that Windows is healthy.
It worked for me.
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February 2, 2017 at 7:49 am #83189
anonymous
GuestQuoted from
http://www.howtogeek.com/222532/how-to-repair-corrupted-windows-system-files-with-the-sfc-and-dism-commands/“On Windows 7 and earlier, the DISM command isn’t available. Instead, you can download and run the System Update Readiness Tool from Microsoft and use it to scan your system for problems and attempt to fix them.”
1 user thanked author for this post.
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February 4, 2017 at 4:40 pm #89418
PhotM
AskWoody PlusYes BUT,
When I was on W 7, the “System Readiness Tool” did not repair anything. That is one of the main reasons I went to W 8(it sure wasn’t the GUI).
Also SFC is much more comprehensive on W 8 and higher and is still being enhanced on W 8.1 and especially W 10.
Best Regards,
Crysta
--------------------------------------
1. Tower Totals: 2xSSD ~512GB, 2xHHD 20 TB, Memory 32GB
SSDs: 6xOS Partitions, 2xW8.1 Main & Test, 2x10.0 Test, Pro, x64
CPU i7 2600 K, SandyBridge/CougarPoint, 4 cores, 8 Threads, 3.4 GHz
Graphics Radeon RX 580, RX 580 ONLY Over Clocked
More perishable2xMonitors Asus DVI, Sony 55" UHD TV HDMI
1. NUC 5i7 2cores, 4 Thread, Memory 8GB, 3.1 GHz, M2SSD 140GB
1xOS W8.1 Pro, NAS Dependent, Same Sony above.-----------------
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February 2, 2017 at 9:08 am #83358
grumpy65867
AskWoody Plus-
February 2, 2017 at 12:52 pm #83869
Noel Carboni
AskWoody_MVP
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February 2, 2017 at 9:53 am #83477
PhotM
AskWoody PlusI do this regularly(albeit with Scannow which actually does some repair) before and after major updates. It has saved me allot of grief and is one of the major reasons I left W 7 SP 1. Here is my script I C&P into Powershell(or CMD):
ReagentC /Info
sfc /scannow
DISM /Online /Cleanup-Image /RestoreHealth
DISM /Online /Cleanup-Image /AnalyzeComponentStore
DISM /Online /Cleanup-Image /StartComponentCleanup
DISM /Online /Cleanup-Image /AnalyzeComponentStoreBest Regards,
Crysta
--------------------------------------
1. Tower Totals: 2xSSD ~512GB, 2xHHD 20 TB, Memory 32GB
SSDs: 6xOS Partitions, 2xW8.1 Main & Test, 2x10.0 Test, Pro, x64
CPU i7 2600 K, SandyBridge/CougarPoint, 4 cores, 8 Threads, 3.4 GHz
Graphics Radeon RX 580, RX 580 ONLY Over Clocked
More perishable2xMonitors Asus DVI, Sony 55" UHD TV HDMI
1. NUC 5i7 2cores, 4 Thread, Memory 8GB, 3.1 GHz, M2SSD 140GB
1xOS W8.1 Pro, NAS Dependent, Same Sony above.-----------------
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February 2, 2017 at 10:35 am #83715
b
AskWoody PlusThe self-healing feature is not called System Protection, which is the Restore Points storage in all versions from WinME to Win10: https://en.wikipedia.org/w/index.php?title=System_Protection&redirect=no
Since Windows 2000, SFC has been part of Windows File Protection which does replace system files:
https://en.wikipedia.org/wiki/Windows_File_Protection1 user thanked author for this post.
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February 2, 2017 at 12:45 pm #83868
Noel Carboni
AskWoody_MVP
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February 2, 2017 at 1:21 pm #83881
ch100
AskWoody_MVP-
February 4, 2017 at 4:51 pm #89467
PhotM
AskWoody PlusAll Updates do way more than One realizes or that MS will ever be prepared to Itemize.
I would think that this will and does pertain especially to built in TOOLS.If a Patch/CU/Security/etc including a necessary Hotfix(not the special very specific ones) includes augmentation to A TOOL, without it the TOOL maybe broken…..
Best Regards,
Crysta
--------------------------------------
1. Tower Totals: 2xSSD ~512GB, 2xHHD 20 TB, Memory 32GB
SSDs: 6xOS Partitions, 2xW8.1 Main & Test, 2x10.0 Test, Pro, x64
CPU i7 2600 K, SandyBridge/CougarPoint, 4 cores, 8 Threads, 3.4 GHz
Graphics Radeon RX 580, RX 580 ONLY Over Clocked
More perishable2xMonitors Asus DVI, Sony 55" UHD TV HDMI
1. NUC 5i7 2cores, 4 Thread, Memory 8GB, 3.1 GHz, M2SSD 140GB
1xOS W8.1 Pro, NAS Dependent, Same Sony above.-----------------
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February 2, 2017 at 2:54 pm #83908
Steve S.
AskWoody PlusThanks, Noel. I just ran sfc /verifyonly on my Win 7 Pro SP 1 that I’ve been running for years now. I have essentially been in Group B since the GWX debacle started in 2015. Results: 100% OK. Now I have some added “warm fuzzies”… 😉
Win7 Pro x64(Group B), Win10 Pro x64 1909, Win10 Home 1909, Linux Mint + a cat with 'tortitude'.
1 user thanked author for this post.
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February 2, 2017 at 4:05 pm #84364
WildBill
AskWoody PlusI followed Noel’s instructions, doing VERIFYONLY 1st, then SCANNOW. SCANNOW indicated problems it couldn’t repair, so I ran DISM, then SCANNOW again. My PC was low on battery power & shut down on the last scan. I ran SCANNOW again & I have the warm fuzzies! This was the 1st time ever running SFC & DISM since I bought my Windows 8 (now 8.1) laptop 4 years ago.
2 Machines for Now!
#1: Windows 8.1, 64-bit, back in Group A.
#2: Getting close to buying a refurbished Windows 10 64-bit, recently updated to v1909. Have broke the AC adapter cord going to the 8.1 machine, but before that, coaxed it into charging. Need to buy new adapter if wish to continue using it.
Wild Bill Rides Again... -
February 2, 2017 at 5:18 pm #84649
Canadian Tech
AskWoody_MVP -
February 4, 2017 at 3:09 pm #89301
Pepsiboy
AskWoody LoungerWoody,
When I try to run sfc (either verifyonly or scannow) all I get is aVERY brief flash of a DOS screen, then nothing else happens. Is there maybe something wrong going on here? Running Win 7 X64 SP1.
I would attach a screen shot, but the flash of a DOS screen only lasts about 1/4 second.
Thanks, in advance for any help or advice.
Dave
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February 4, 2017 at 3:14 pm #89306
Canadian Tech
AskWoody_MVP -
February 5, 2017 at 10:59 am #90638
WildBill
AskWoody PlusTry running Windows PowerShell (admin) if it’s available on Windows 7. That’s where I ran SFC instead of the Command Prompt.
2 Machines for Now!
#1: Windows 8.1, 64-bit, back in Group A.
#2: Getting close to buying a refurbished Windows 10 64-bit, recently updated to v1909. Have broke the AC adapter cord going to the 8.1 machine, but before that, coaxed it into charging. Need to buy new adapter if wish to continue using it.
Wild Bill Rides Again... -
February 14, 2017 at 8:02 pm #94145
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February 4, 2017 at 4:39 pm #89409
Pepsiboy
AskWoody Lounger-
February 4, 2017 at 4:43 pm #89424
Canadian Tech
AskWoody_MVPSorry, no idea. I have never seen that. Have you run a malware scanner? I use ADWcleaner:
https://toolslib.net/downloads/viewdownload/1-adwcleaner/CT
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February 4, 2017 at 4:50 pm #89466
PKCano
Da BossSomewhere I remember there was a KB that was supposed to repair SFC functionality. Don’t remember the particulars. Sept last year, I think, KB3181988. Seems like it didn’t come through WU, you had to download it from the Catalog. It can’t hurt anything to try. Be sure you get the right bitedness and the right version. http://www.catalog.update.microsoft.com/Search.aspx?q=3181988
1 user thanked author for this post.
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February 4, 2017 at 5:12 pm #89506
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February 5, 2017 at 12:07 pm #90692
PhotM
AskWoody PlusTry running Windows PowerShell (admin) if it’s available on Windows 7. That’s where I ran SFC instead of the Command Prompt.
Begging your Pardon Sir,
But one needs AT LEAST CMD(Command Prompt) as Admin(elevation) to run SFC. I do usually use Powershell and it CAN be Installed on W 7. See the Following:
Install and configure WMF 5.1 https://msdn.microsoft.com/en-us/powershell/wmf/5.1/install-configure
Windows Management Framework (WMF) 5.1 Released | Windows PowerShell Blog https://blogs.msdn.microsoft.com/powershell/2017/01/19/windows-management-framework-wmf-5-1-released/
WMF 5.1 Release Notes https://msdn.microsoft.com/en-us/powershell/wmf/5.1/release-notes
PowerShell Magazine » Comparing commands between PowerShell versions http://www.powershellmagazine.com/2016/04/29/comparing-commands-between-powershell-versions/
PowerShell Gallery | Home https://www.powershellgallery.com/
Get Started with the PowerShell Gallery | MSDN https://msdn.microsoft.com/en-us/powershell/gallery/psgallery/psgallery_gettingstarted
The PowerShell Gallery | MSDN https://msdn.microsoft.com/en-us/powershell/gallery/readme
There are many more but one will find them through all of the above, for those whom are interested. Also keep a watch on @jsnover on Twitter the Father of Powershell.
For clarification, I am still a novice BUT I do find PS and PS ISE(for the Module memory joggers) fascinating. However I do prefer GUI’s the most.
Best Regards,
Crysta
--------------------------------------
1. Tower Totals: 2xSSD ~512GB, 2xHHD 20 TB, Memory 32GB
SSDs: 6xOS Partitions, 2xW8.1 Main & Test, 2x10.0 Test, Pro, x64
CPU i7 2600 K, SandyBridge/CougarPoint, 4 cores, 8 Threads, 3.4 GHz
Graphics Radeon RX 580, RX 580 ONLY Over Clocked
More perishable2xMonitors Asus DVI, Sony 55" UHD TV HDMI
1. NUC 5i7 2cores, 4 Thread, Memory 8GB, 3.1 GHz, M2SSD 140GB
1xOS W8.1 Pro, NAS Dependent, Same Sony above.-----------------
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March 2, 2017 at 6:57 am #98216
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May 28, 2017 at 5:59 pm #118480
_Reassigned Account
AskWoody LoungerRan SFC /verifyonly on Win 7 SP1 x64 Pro. Got many errors, most of which point to all the files I deleted on one of my cleaning binges. Files are all the unused language files I do not need. Files located in various places in Windows and its sub-directories. Any cause for concern? Why must I keep the unused files of various languages? Did not delete various kbd files, too time consuming to figure out who’s who? Tnx.
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February 2, 2019 at 12:37 pm #319977
bbearren
AskWoody MVPFWIW, I never run any of the Windows tools in the “check” or “analyze” mode, I always run them in their repair mode. If there’s nothing wrong, I still get the “OK” from the tool, but if there is something wrong, I don’t have to re-launch the tool for a second run.
If the Dism tool can’t effect repairs (which does happen on occasion) I use my installation media and run this command line:
dism /online /cleanup-image /restorehealth /source:X:\repairsource\windows /limitaccess
where X is the drive letter assigned by File Explorer when the media is plugged in.
Create a fresh drive image before making system changes/Windows updates, in case you need to start over!"When you're troubleshooting, start with the simple and proceed to the complex."—M.O. Johns"Experience is what you get when you're looking for something else."—Sir Thomas Robert Deware1 user thanked author for this post.
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