System File Checker (sfc)

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

•

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 <a class=”dynavar” onclick=”javascript:toggle_dynamic_var(“systemroot”);” title=”Click to edit dynamic variable: systemroot”>No value assigned\system32\dllcache folder, and then replaces the incorrect file.

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If the No value assigned\system32\dllcache folder becomes corrupt or unusable, use sfc /scannow, sfc /scanonce, or sfc /scanboot to repair the contents of the Dllcache directory.