Computers And Industry

System File Checker Restores Corrupt Windows System Files


The System File Checker is a Windows utility application that compares your current critical Windows Operating System Files to a known valid set of critical Windows Operating System files and replaces any corrupt system files with the copy of it's valid counterpart. If there are any anomalies in the way your computer is running, it is always prudent to first run the System File Checker.

If The Computer Boots Normally And You Can Log In

1. Right Click The Mouse on the Start Menu button and select Command Prompt (Admin). A command window will open up.
2. Enter sfc /VERIFYONLY and press Enter. This will perform an intial scan on your system files but WILL NOT make any changes. The results of the process will be written to a log file located in the C:\Windows\Logs\CBS folder.
3. If there are no errors, then great. You do not have to do anything else. Type in exit in the command window to go back to normal Windows. HOWEVER, if you did receive errors, proceed with the next step.
4. Enter in the command sfc /SCANNOW and press Enter. This will repeat the process but this time, any corrupt files will be replaced. The results of the process will be written to a log file located in the C:\Windows\Logs\CBS folder.
5. Upon completion of the process, you will be notified of the results of the operation. If there are any discrepancies, check the log file for specifics.
6.. Enter Exit in the command window to go back to normal Windows.

If You Started Your Computer Using A Windows Recovery USB Drive

Before the System File Checker utility can be run in recovery mode, it is necessary to first get to a Command Window. To do this in recovery mode, please do the following.

(1) If you started the computer from the Windows Recovery USB Drive, and are staring at a blue screen that asks you to select your keyboard, select US (or whatever language you require). (2) On the Choose an Option screen, select TroubleShoot. (3) On The Troubleshoot screen, select Advanced Options. (4) On the Advanced Options screen, select Command Prompt. You will now have a command window in which system utilities can be run. (You will see a command prompt something like X:>

1. Since the computer was booted from a recovery drive, technically, it knows nothing about the Windows installed on the computer. Thus, when running the utility, it is necessary to tell the utility where the windows installation is located. But where is the Windows Installation Located? To find out

Enter the command fsutil fsinfo drives and the press Enter.

A list of drives will appear (i.e. C:, D:, E:) Now, it is necessary to inspect each drive to see if it contains the Windows installation. Note IT IS NOT ALWAYS THE C drive!. To do this. repeat the following for each drive.

(1). Enter C: (or any other drive letter) and press Enter.
(2). Enter in Dir and press Enter
(3). Look for a folder named Windows in the list. If it is found, write it down. If not found, repeat steps 1 - 3 for each drive

2. Enter in the command sfc /SCANNOW /OFFBOOTDIR=C:\ /OFFWINDIR=C:\Windows and then press Enter. The System File Check process will begin. It will take quite a bit of time so sit back and relax.
3. If everything is OK, i.e. System Windows Resource Protection doesn't find any errors, then great. If it did find errors, then type Exit and then Enter at the command prompt, reboot, and repeat steps 1 through 3 again until no more errors. In all honesty, this might have to be repeated 3 or 4 times until no errors are encountered.

Note. If the System File Checker will not run even once, then the Deployment Image Servicing and Management (DISM) utility must be run to restore the Windows image to a working condition. The DISM utility is explained in a different post.

System File Check Utility Command line options

The System File Check utility has several command line options which alter the operating characteristics of the utility. They are as follows.

/? Displays a help screen about the utility
/VERIFYONLY This option causes the utility to only verify the system files. It will not replace them.
/SCANNOW This options verifies and then fixes any discrepancies encountered.
/VERIFYFILE This option only verifies a specific file for any discrepancies. The format is /VERIFYFILE=C:\Windows\System32\kernel.dll
/SCANFILE This option scans a specific file for discrepancies. The format is /SCANFILE=C:\Windows\System32\kernel.dll
/OFFBOOTDIR Tells the utility which drive is the normal boot drive. Used primarily when booting from a recovery drive
/OFFWINDIR Tells the utility in which folder Windows is installed.

Concluding, the System File Check utility compares and repairs Windows system files. It may be used during normal operations as well as in recovery mode. The System File Check utility is not the total solution when repairing a Windows system but it is an important part of the process.

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