System File Checker
Updated: January 21, 2005
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.
- 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
| Format | Meaning |
| Italic | Information that the user must supply |
| Bold | Elements that the user must type exactly as shown |
| Ellipsis (...) | Parameter that can be repeated several times in a command line |
| Between brackets ([]) | Optional items |
| Between braces ({}); choices separated by pipe (|). Example: {even|odd} | Set of choices from which the user must choose only one |
| Courier font | Code or program output |