Windows command guide

How to Use SFC /scannow to Repair Corrupted Windows System Files

The System File Checker command is one of the most searched Windows repair commands for a reason. When core system files become damaged, Windows can start behaving in strange ways even if the hardware is fine. Apps may crash, settings pages may fail to open, and built-in components can stop responding. SFC compares protected Windows files against trusted copies and replaces files that no longer match what the operating system expects.

This guide is written around the specific symptom-command match for repair corrupted system files, not as a generic dump of terminal lines. That makes the page more useful for real troubleshooting and reduces the chance of running the wrong repair step.

Reviewed guide Updated 2026-04-21

Elevated Command Prompt

sfc /scannow

Best place to run it

Elevated Command Prompt is the right execution context for this page. Because this repair touches protected Windows state, a normal unelevated shell can return misleading access errors or partial results.

Fast repair workflow

Start from the exact symptom on this page: Windows features open slowly or fail to launch at all
Run the primary repair line exactly as shown: sfc /scannow.
This workflow is tuned for this repair, so avoid mixing it with unrelated repair commands too early.
Reboot if the servicing stack or protected files were changed, then retry the original Windows action.
Escalate only after reading the output, usually toward CBS.log, DISM source repair, or Windows Update-specific repair.

Copyable wrapper script

Use this wrapper when you want the page command inside a clearer script block with start and finish prompts.

@echo off
echo Run this CMD sequence in an elevated Command Prompt.
echo Starting targeted repair sequence...
sfc /scannow
echo.
echo Review the output before closing this window.
pause

Verification commands after the repair

These follow-up commands help you check whether the repair actually changed the Windows state that matters, instead of assuming success from a single line.

findstr /c:"[SR]" %windir%LogsCBSCBS.log
sfc /verifyonly

What problem this command is trying to solve

This command targets corruption inside protected Windows system files. That kind of corruption can appear after interrupted updates, sudden power loss, storage problems, malware cleanup, or software that modified system components in the wrong way.

Windows features open slowly or fail to launch at all.
Built-in tools such as Settings, File Explorer, or Windows Security behave unpredictably.
You see unexplained errors after an update or system crash.

How the command works

When you run sfc /scannow in an elevated Command Prompt, Windows starts a full scan of protected system files. It checks each file against the component store and attempts to replace invalid versions automatically.

When it makes sense to run it

Run SFC when Windows itself seems unstable, not just one third-party app. If the scan reports that it found corruption but could not fix everything, the next step is often DISM /RestoreHealth.

Before you run this command

Open an elevated Command Prompt or PowerShell window before running sfc /scannow.
Confirm that the symptom really matches this guide, especially if you are seeing signs such as: windows features open slowly or fail to launch at all.
Keep any exact DISM, SFC, CBS, or Windows Update error output because those details matter in the next step.

What result to expect

After running sfc /scannow, compare the result against the symptom that brought you here. The most useful checkpoint is whether windows features open slowly or fail to launch at all becomes less frequent, changes form, or produces a clearer error message. A command page is stronger when it helps you verify a real change instead of just assuming the line must have worked.

How to verify that it worked

The best verification step after sfc /scannow is to repeat the action that previously triggered the problem. If built-in tools such as settings, file explorer, or windows security behave unpredictably still appears in exactly the same way, the command probably was not the whole answer and you should move to the next targeted check instead of assuming the page is finished.

Why administrator rights matter here

This command changes system integrity and component corruption. Run it in an elevated shell so Windows can apply the repair instead of only returning an access or privilege error.

Before you run it

Open Command Prompt as administrator. Avoid interrupting the scan once it starts. If the machine has serious disk errors, it can be worth checking storage health too.

When this is probably the wrong fix

This is not the right first fix for a single third-party app bug, a browser-only issue, or obvious hardware failure. Use it when the symptom points to Windows image health, recurring update corruption, or protected system files.

What to do if it does not help

If sfc /scannow does not improve windows features open slowly or fail to launch at all, move to the next repair step that matches the same symptom family instead of piling on random commands. The best follow-up depends on whether the failure is mainly about system integrity and component corruption.

Frequently asked questions

Should I use sfc /scannow for this exact Windows symptom?

Use it when the behavior on your PC lines up with the repair target on this page: This command targets corruption inside protected Windows system files. That kind of corruption can appear after interrupted updates, sudden power loss, storage problems, malware cleanup, or software that modified system components in the wrong way.

What should I check right after sfc /scannow?

Check whether the original trigger still reproduces the same failure. For this page, a useful checkpoint is whether windows features open slowly or fail to launch at all becomes less frequent, changes form, or points you toward a more specific next step.