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Fix Corrupted Windows System Files with SFC and DISM

Oct 16, 2026 · Windows · 3 min read

Random crashes, apps that won't open, Windows Update failing with odd error codes, a broken Start menu: these are classic signs of corrupted system files. Windows has two built-in tools for this, and the order you run them in matters.

Run everything below in an elevated terminal: right-click Start → Terminal (Admin) or Command Prompt (Admin). Works on Windows 10 and 11.

The short version

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Run DISM first, then SFC. Restart afterwards.

What each tool does

Tool Repairs Needs
SFC (System File Checker) Replaces damaged protected files from the local component store Nothing
DISM Repairs the component store itself, which is SFC's source of good files Internet (Windows Update) or a Windows image

If the store is damaged, SFC has nothing good to copy from and fails. That's why DISM comes first.

Step 1: check and repair the component store

DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
  • CheckHealth is a quick check for existing damage flags.
  • ScanHealth scans thoroughly, taking several minutes.
  • RestoreHealth repairs, downloading replacement files from Windows Update.

It's normal for the progress bar to sit at 20% or 62% for a long time. Don't cancel it. Details are in C:\Windows\Logs\DISM\dism.log.

Step 2: scan and repair system files

sfc /scannow

Possible results:

Message Meaning
did not find any integrity violations Files are fine. Look elsewhere (drivers, software)
found corrupt files and successfully repaired them Done. Restart
found corrupt files but was unable to fix some of them Run DISM (step 1), then SFC again
could not perform the requested operation Run it from Safe Mode or from the recovery environment

Extract the details of what SFC could not repair:

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log > "%userprofile%\Desktop\sfc-details.txt"

SFC often needs two or three runs to settle. Run it until it reports clean.

If DISM cannot download files

Use a Windows ISO of the same version as the source. Mount it (right-click → Mount) and note the drive letter (here D:):

DISM /Online /Cleanup-Image /RestoreHealth /Source:WIM:D:\sources\install.wim:1 /LimitAccess

If your ISO contains install.esd instead of install.wim, use /Source:ESD:D:\sources\install.esd:1. The index (:1) must match your edition, and you can list them with DISM /Get-WimInfo /WimFile:D:\sources\install.wim.

If Windows won't boot

Boot from the installation USB → Repair your computer → Troubleshoot → Command Prompt, then run SFC against the offline installation:

sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

The drive letter of Windows can differ in recovery mode, so check with dir C:\.

Also check the disk

File corruption is often a symptom of a failing disk:

chkdsk C: /scan

Check health from PowerShell:

Get-PhysicalDisk | Select FriendlyName, MediaType, HealthStatus

A disk reporting Warning or Unhealthy needs replacing. Back up your data first.

Last resorts

  1. System Restore to a point before the problem started (rstrui).
  2. Settings → System → Recovery → Reset this PC → Keep my files. This reinstalls Windows and keeps your personal files, but apps need reinstalling.
  3. An in-place repair upgrade: run setup.exe from a matching ISO and choose Keep personal files and apps.
dismsfctroubleshootingwindows