Command Reference
sfc /scannow
Gnojo Analysis
Understanding sfc /scannow
What This Command Does
Scans protected Windows files and attempts to replace corrupted copies. Microsoft recommends updating and restarting Windows, then completing DISM RestoreHealth before this repair command.
When to Use It
Use sfc /scannow when troubleshooting system integrity issues and you need information that can help narrow down the cause.
What to Look For
Windows Resource Protection did not find integrity violations
No protected-file corruption was detected.
found corrupt files and successfully repaired them
Windows replaced one or more damaged protected files.
found corrupt files but was unable to fix some
Further component-store analysis may be required.
Permissions
Run this command from an elevated terminal with administrator access.
Risk and impact
SFC may replace protected Windows files. Save work, follow Microsoft's recommended DISM-then-SFC sequence, and do not interrupt the scan.
Typical Next Steps
Continue troubleshooting with one of these related commands:
Summary
Scans protected Windows files and attempts to replace corrupted copies. Microsoft recommends updating and restarting Windows, then completing DISM RestoreHealth before this repair command.
Syntax
sfc /scannowExamples
sfc /scannowRuns a complete protected-system-file scan from an elevated Command Prompt after the recommended DISM repair step.
Permissions
Administrator required: Yes
Run only from Command Prompt opened as administrator and follow organizational change policy.
Risk and Impact
Risk level: Moderate
Changes the system: Yes
SFC may replace protected Windows files. Save work, follow Microsoft's recommended DISM-then-SFC sequence, and do not interrupt the scan.
Supported Platforms
Important Output Fields
Windows Resource Protection did not find integrity violations
No protected-file corruption was detected.
found corrupt files and successfully repaired them
Windows replaced one or more damaged protected files.
found corrupt files but was unable to fix some
Further component-store analysis may be required.
Common Errors
You must be an administrator
The terminal was not opened with elevated rights.
There is a system repair pending
Complete the pending restart or servicing operation first.
Related Commands
Continue troubleshooting with related diagnostic commands.
Official References
Using System File Checker in Windows
Microsoft Support · Official Documentation