The System File Checker (SFC) is a preinstalled Command Prompt tool in Windows that attempts to repair corrupted system files by replacing them with redundant files. However, this also requires that the system image is healthy, so it can perform a successful repair. SFC is a mechanism of the Windows File Protection feature. Show
Advertisement The SFC tool comes with several switches that perform different functions. Today we will talk about how to perform a successful SFC scan on your Windows computer, and how to troubleshoot any errors that you may encounter along the way. We will also discuss the contingent tools on which the SFC scan relies. Table of contents
SFC SwitchesThe table below lists all the switches which can be used with the SFC command-line tool and their functions:
Today, we are only going to be focusing on the “sfc /scannow” cmdlet as it is the one that quickly and effectively fixes your operating system. Running Basic SFC ScanThe simplest (and most convenient) method to run an SFC scan is by running the following cmdlet in an elevated Command Prompt:
The cmdlet will then perform its job and attempt to repair any protected system files that may have been corrupted. However, that is not always the case, and users may encounter different errors from time to time. Before we discuss these different errors, let us discuss the various outputs of the basic scan and what each of those means. Outputs of SFC ScanAs you can observe in the image above, the output of the SFC scan states the following: Windows Resource Protection found corrupted files and successfully repaired them. It then also states the location of a CBS.log file which contains the details of the performed scan – we’ll get into that a moment later. Let us now see all the possible outputs of the SFC scan that different users can encounter, and what they mean:
Apart from these, there are other possible issues that you may encounter while performing the scan. Why SFC Scan FailedYou can encounter any one of the following scenarios while performing an SFC scan. The table below lists those scenarios along with their possible solutions. Note: The methods to perform these solutions are discussed below.
Before we discuss the different methods to run the SFC scan, bypassing any issues, let us look at the log file generated when an SFC scan is executed. How to Open SFC CBS.Log FileWhen you perform an SFC scan, the system automatically generates a log file named “CBS.log.” This file contains information on the scan that was executed, which can help you advanced troubleshoot if you encounter an issue with the SFC tool. The CBS.Log file is saved at the following location: C:\Windows\Logs\CBS You can open this log file using a text editor, such as Notepad, Word, Wordpad, etc. Follow these steps to open the file:
The log file will then open in the text editor. Since the CBS.Log file can be lengthy, you can analyze it using the Find function. You can look for keywords in the entire file using the CTRL + F shortcut keys, and then use the following keywords to look for the details on the file that may have been repaired, not repaired, corrupted, etc. Here is a list of the keywords you can use and the respective features you can find.
By analyzing the CBS.Log file, you can pinpoint the files which SFC could not repair, and then replace those files manually using the guide given down below. How to Fix SFC /ScanNow FailedIf you are not able to fix your operating system using the basic approach for running the SFC scan, then there is still plenty you can do to mitigate the problem. Note: The below methods need to be performed using only an administrative account and any commands need to be run using an elevated Command Prompt. Note: The steps given below need to be performed in a methodical order as given.
That is it! This method should eliminate any issues you experience while performing the SFC scan in basic mode. Restart the computer once the scan is complete. However, if you find the SFC utility is still unable to fix missing or corrupted files, there are still several things you can do. To begin, we suggest you analyze the CBS.Log file, as we discussed earlier in this post. Run Offline SFC ScanNow from WinPEThe offline version of the SFC scan means that you run the scan from the Windows Preinstallation Environment (WinPE). This method can be especially useful if you are unable to boot into Windows. This process requires a Windows installation device (DVD, bootable USB) that has the same OS version as installed. Perform the following steps to attempt and repair any missing or corrupted system files using the SFC scan with WinPE.
If this does not work for you either, you can manually replace the corrupted files yourself. Manually Replace Corrupted FilesAt this point, you must have already analyzed the VBS.Log file we had discussed earlier. Using the file names determined from there, you can manually replace them with healthy files obtained from another computer. Here is how to do it:
That is it! You can now repeat the same process to manually replace any corrupted files. Scan Other Non-OS Volumes using SFCIt may be possible that you are running more than one operating system on your PC, and not all of them can be in the same drive (usually the C drive). In that case, you must direct the SFC scan to attempt and repair another drive. Furthermore, you can also direct it to scan external drives, such as USB flash drives, SD cards, etc. Here is how to do so: Note: Since SFC can only fix missing and corrupted system files, it can only attempt to repair drives with a Windows operating system in it.
The scan will now attempt to repair any corrupted or missing files that you selected other than the C drive. How to Fix “Windows Resource Protection Could Not Start The Repair Service”It may be possible that you encounter the following error while trying to run an SFC scan on your computer: Windows Resource Protection could not start the repair service If so, here are a few things you can do to mitigate this issue: Start Dependency ServiceIt may be possible that a dependency service named “Windows Modules Installer (Trusted Installer)” isn’t running on your computer, preventing the scan from happening. In that case, the service needs to be enabled.
Learn other methods to enable and disable Windows services. Disable Turbo MemoryIntel Turbo Memory is a feature that allows NAND memory modules to power up, access programs, and write data on the hard drive much quicker than usual. This feature can be controlled through the system BIOS. If you experience an SFC scan suddenly stops or cannot complete its job, then you must disable Turbo Memory from the BIOS settings. Learn how to access BIOS. Modify Security DescriptorsA Security Descriptor contains security information that may be associated with a securable object. It may be possible that critical Security Descriptors may have corrupted in the WinSXS folder where critical system files are stored. To mitigate this issue, perform the following task:
Other Mitigation MethodsIf you encounter the said error, there are other things you can also perform which we have already discussed above in this post. Here is a list of additional steps you can take:
Frequently Asked QuestionsDoes SFC ScanNow fix anything?Short answer: Yes, it does. However, the SFC tool itself can occasionally encounter errors, which are also fixable. How to run SFC scan?Run
the following cmdlet in the Command Prompt: Is the SFC scan safe?Yes, the SFC scan is completely safe. In fact, you can even run it if nothing is wrong with your computer, just to ensure your device’s integrity. What does SFC ScanNow actually do?The SFC ScanNow cmdlet scans all protected system files and replaces corrupted files with a cached copy that has been kept in its original shape. Can you exit SFC scannow?Yes, it is safe to cancel the scan. However, we do suggest that you allow it to be completed as it causes no harm. If you find that it is stuck you can cancel it using the CTRL + C keys simultaneously. Does SFC ScanNow improve performance?If the scan is able to fix critical system files, it can sometimes improve the system’s overall performance and speed since the protected files are now as they should be. Can SFC ScanNowfix BSoDs?Potentially, yes. BSoDs are often caused by corrupted or missing system files, and this is the one thing SFC is good at. Also see: Subscribe to our NewsletterGet the latest tech news, advice and downloads in your inbox What is the command to use the System File Checker to immediately verify and repair system files quizlet?What is the command to use the System File Checker to immediately verify system files? To verify system files on the next restart? sfc /scannow - To verify system files on the next restart check the box on the dialog "on the next restart."
What is the System File Checker command?Short for System File Checker, SFC is a command that scans and replaces any Microsoft Windows file with the correct version. The sfc command is excellent when you run into an issue that is difficult to troubleshoot.
What tool should you use to verify and replace system files?Windows System File Checker (SFC) tool can be used to check the System Files for errors or corruption and fix them. SFC basically scans the integrity of system files on your computer and automatically replaces them with correct version files, in case they are found to be missing, corrupted, damaged or changed.
How do I run System File Checker and DISM?DISM command with CheckHealth option
Open Start. Search for Command Prompt, right-click the top result, and select the Run as administrator option. Type the following command to perform a quick check and press Enter: DISM /Online /Cleanup-Image /CheckHealth.
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