System File Checker is an in-built utility that allows users to scan for & repair corruptions within a Windows operating system.
It is possible that your computer may have underlying issues & corrupt system files yet on the face of it run perfectly normally, at least until such time that any corrupt system files may be required to run or be called upon for operation. Any complete PC Health check should encompass a full ‘system file check’. This would involve scanning & restoration of any corrupted system files by matching their version number against a database containing the original version number of the files that were within a fresh Windows installation. System File Checker in the latest Windows operating systems can scan specific individual files. Also, scans can be performed against an online Windows installation folder to replace corrupt files.
In order to perform a system file check you simply need to open a command prompt with administrator privileges & type:
sfc /scannow
If a problem is found, attempts to replace the problematic files will be undertaken & you may be prompted to insert Windows installation media.
If during a system file check Windows Resource Protection does find corrupt files & for whatever reason is unable to fix some of them. Details would usually be presented in a Log file (for example C:\Windows\Logs\CBS\CBS.log).
This, however, would mean that the corrupt system files were unable to be successfully repaired at all, & it may be necessary to reformat your entire operating system for a clean bill of health.
If however an element within Windows 8(.1) or 10 becomes unserviceable, you can even use an inbuilt Deployment Imaging and Servicing Management (DISM) tool to update the files & correct the problem from an online image. This online Windows image will even attempt to repair itself if it becomes unserviceable.
To fix irreparable, corrupt files that were unable to be successfully repaired by a system file check in Windows 8(.1) or 10, all you need to do is open another command prompt with administrator privileges & type:
dism /online /cleanup-image /restorehealth
DISM (Deployment Image & Servicing Management) is tool that is used to fix component store corruption that prevents SFC from running properly. Basically, if SFC is corrupt and doesn’t work for some reason you can use DISM to restore it. Wait for the scan to be performed, it can take a while. If the progress bar gets stuck on 20 percent, don’t worry, that’s perfectly normal, you just need to be patient. After DISM has finished its scan, restart your computer.
If DSIM reports that it cannot find the source files, then they are missing or have simply not been located on your computer. You will need to obtain an install.WIM file from a known good Windows disc or ISO (Note that most image files now contain an ESD image, which will not work for the repair).
If the source files are required to repair corrupt files in Windows 10, you need to get Windows 10 ISO file. Note the conventional Media Creator tool will not work because that image has an Electronic Software Distribution file (ESD)- not a WIM file which is required for the following command to work). Right click & Mount the ISO file, then Run command as administrator:
DISM /Online /Cleanup-Image /RestoreHealth /source:WIM:D:\Sources\Install.wim:1 /LimitAccess
(Remember to replace D if necessary with the correct letter drive on which your Windows 10 ISO has been mounted). Restart your computer and try SFC again.
