Scans and verifies the versions of all protected system files after you restart your computer.
Syntax
sfc [/scannow] [/scanonce] [/scanboot] [/revert] [/purgecache] [/cachesize=x]
Parameters
/scannow
: Scans all protected system files immediately.
/scanonce
: Scans all protected system files once.
/scanboot
: Scans all protected system files every time the computer is restarted.
/revert
: Returns the scan to its default operation.
/purgecache
: Purges the Windows File Protection file cache and scans all protected system files immediately.
/cachesize=x
: Sets the size, in MB, of the Windows File Protection file cache.
/?
: Displays help at the command prompt.
Remarks
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You must be logged on as a member of the Administrators group to run sfc.
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If sfc discovers that a protected file has been overwritten, it retrieves the correct version of the file from the %systemroot%\system32\dllcache folder, and then replaces the incorrect file.
-
If the %systemroot%\system32\dllcache folder becomes corrupt or unusable, use sfc /scannow, sfc /scanonce, or sfc /scanboot to repair the contents of the Dllcache directory.
Formatting legend
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Meaning
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Italic
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Information that the user must supply
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Bold
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Elements that the user must type exactly as shown
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Ellipsis (...)
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Parameter that can be repeated several times in a command line
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Between brackets ([])
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Optional items
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Between braces ({}); choices separated by pipe (|). Example: {even|odd}
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Set of choices from which the user must choose only one
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Courier font
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Code or program output
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Windows File Protection
Using File Signature Verification
Driver Signing for Windows
Command-line reference A-Z