SFC, DISM and CHKDSK: What Each One Does and the Right Order to Run Them
Windows 11 is crashing, Windows Update is failing or system files appear corrupted, so you search online and immediately encounter three commands:
DISM.exe /Online /Cleanup-Image /RestoreHealth
sfc /scannow
chkdsk C: /f
They are often thrown together as though they perform the same repair.
They do not.
The simplest answer is:
For ordinary Windows corruption:DISM /RestoreHealth → SFC /scannow → restart
If you suspect file-system errors:CHKDSK /scan → repair if required → DISM → SFC
If you suspect the storage device itself may be failing:
Back up important data and investigate the drive before repeatedly running repair commands.
Microsoft specifically recommends running DISM before System File Checker because DISM provides the Windows components that SFC may need to replace damaged system files.
CHKDSK has a different job entirely: it checks the file system and file-system metadata of a drive for logical and, with certain options, physical errors.
Here is what each command actually does and when you should use it.
What Does SFC /scannow Do?
SFC stands for System File Checker.
Its purpose is to inspect protected Windows system files and replace damaged or missing files where Windows has a suitable replacement available. Microsoft describes SFC as a tool for finding and repairing corruption that can cause Windows features to malfunction, system errors, freezes and other instability.
Open Terminal or Command Prompt as Administrator and run:
sfc /scannow
Let the scan reach 100%.
Microsoft says SFC can return several results.
“Windows Resource Protection did not find any integrity violations”
SFC did not detect missing or corrupted protected Windows system files.
That does not necessarily mean there is nothing wrong with the computer.
Your problem could instead involve an application, driver, update, storage device, user profile, hardware component or another part of Windows outside SFC's remit.
“Windows Resource Protection found corrupt files and successfully repaired them”
That is the result you want.
Restart the PC and test the original problem again.
Do not assume the fault has been solved simply because the command completed successfully. If File Explorer was crashing, test File Explorer. If Windows Update was failing, retry Windows Update.
“Windows Resource Protection found corrupt files but was unable to fix some of them”
This is where DISM becomes especially important.
SFC may know that a protected Windows file is damaged but not have a healthy component available from which to replace it.
Microsoft therefore recommends repairing Windows with DISM and then running SFC.
What Does DISM Do?
DISM stands for Deployment Image Servicing and Management.
For this type of troubleshooting, its important job is repairing the Windows image and component store that Windows servicing relies upon.
Run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
Microsoft's current repair instructions explicitly place this command before SFC.
The important parts are:
/Online — work on the Windows installation currently running.
/Cleanup-Image — perform servicing operations on the Windows image.
/RestoreHealth — detect component corruption and attempt to repair it.
DISM normally uses Windows Update to obtain repair files when they are needed. Microsoft also documents the ability to specify another repair source if Windows Update itself cannot provide the required components.
An example is:
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows /LimitAccess
Do not blindly copy that command. The repair source needs to be appropriate for the Windows installation being repaired.
For an ordinary Windows 11 PC with working Windows Update access, start with the normal RestoreHealth command.
Should You Run CheckHealth and ScanHealth First?
You may see troubleshooting guides recommend:
DISM /Online /Cleanup-Image /CheckHealth
then:
DISM /Online /Cleanup-Image /ScanHealth
then:
DISM /Online /Cleanup-Image /RestoreHealth
There is nothing inherently wrong with checking an image before attempting a repair, but for normal troubleshooting Microsoft’s consumer guidance goes directly to:
DISM.exe /Online /Cleanup-Image /RestoreHealth
and then:
sfc /scannow
There is usually little benefit in turning three commands into a ritual when you already intend to perform the repair.
What Does CHKDSK Do?
CHKDSK solves a different class of problem.
It checks the file system and file-system metadata on a volume rather than repairing Windows protected system files or the Windows component store.
That makes it useful when symptoms suggest storage or file-system corruption.
For example, you might investigate the disk if Windows reports file-system errors, files become unreadable, a volume repeatedly needs checking or other evidence points toward storage rather than simply Windows component corruption.
The important point is:
CHKDSK should not automatically be run just because Windows is behaving strangely.
If Windows Update has failed once or one application keeps crashing, that alone is not a reason to launch a lengthy disk repair.
Start With CHKDSK /scan
For an NTFS Windows volume, a good initial check is:
chkdsk C: /scan
Microsoft documents /scan as an online NTFS scan.
This means you can investigate the file system without immediately committing yourself to an offline repair or lengthy sector scan.
If it comes back clean, you have useful information.
If it identifies a problem requiring repair, you can escalate appropriately.
What Does CHKDSK /f Do?
Run:
chkdsk C: /f
The /f option tells CHKDSK to fix file-system errors. Microsoft notes that the volume must be locked to carry out these repairs.
Because Windows is actively using the system drive, you may be asked whether you want the volume checked the next time the computer restarts.
If Windows displays:
Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)
enter:
Y
and restart the computer.
Use /f because you have reason to repair file-system errors, not because it appears on every Windows troubleshooting website.
What Does CHKDSK /r Do?
This is the option people most frequently run unnecessarily.
chkdsk C: /r
Microsoft documents /r as locating bad sectors and attempting to recover readable information. It also includes the functionality of /f.
That makes it substantially different from a straightforward logical file-system repair.
Do not treat /r as a routine Windows maintenance command.
If there are indications that a storage device may have physical problems, protecting the data should take priority over repeatedly stressing the drive with increasingly aggressive repair operations.
If important business data exists only on that device, make sure the backup position is understood before proceeding.
So What Is the Correct Order?
There isn't one universal sequence because the commands repair different things.
Windows is unstable but the drive appears healthy
Run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
Then:
sfc /scannow
Restart Windows and test the original problem.
That follows Microsoft’s documented DISM-before-SFC sequence.
You have evidence of file-system problems
Start with:
chkdsk C: /scan
If CHKDSK identifies errors requiring repair, use the appropriate repair option such as:
chkdsk C: /f
Then, once the file system is healthy, run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
followed by:
sfc /scannow
Microsoft documents /scan as an online NTFS scan and /f as the option that fixes disk errors.
You suspect physical storage failure
Do not simply progress from:
/scan → /f → /r
as though they were levels in a computer game.
Check your backup situation and investigate the health of the storage device.
Microsoft describes /r specifically as checking for bad sectors and recovering readable information, so its purpose is substantially deeper than an ordinary file-system check.
DISM Appears Stuck — Should You Cancel It?
DISM can appear to remain at the same percentage for some time while work continues.
Unless the process has clearly failed or produced an error, avoid assuming a temporarily stationary percentage means the command is frozen.
The important result is the final message from DISM.
Likewise, Microsoft specifically warns not to close the SFC Command Prompt before verification reaches 100%.
What If DISM Cannot Find the Source Files?
DISM normally obtains required repair content through Windows Update.
If Windows Update is unavailable or damaged, Microsoft allows administrators to provide another Windows installation, network location or removable-media source instead.
This is where troubleshooting becomes more technical because the repair source has to be appropriate for the Windows installation you are fixing.
If you encounter errors such as source files not being found, repeatedly changing DISM switches without understanding the installed Windows build is unlikely to be productive.
What If DISM and SFC Still Don't Fix Windows 11?
Windows 11 now has another extremely useful repair option that many older troubleshooting guides do not mention.
Open:
Settings > System > Recovery
Look for:
Fix problems using Windows Update
and select:
Reinstall now
Microsoft says this reinstalls the same version of Windows, repairs system files and components, and preserves your applications, files and settings.
That makes it a valuable escalation step when Windows itself is damaged but you do not yet want to perform a traditional clean installation.
Microsoft notes that the option may not appear on some PCs, particularly devices whose updates are managed by an organisation.
For a business-managed computer, speak to your IT provider before attempting a repair installation.
Don't Use These Commands as a Monthly Maintenance Routine
SFC, DISM and CHKDSK are troubleshooting tools.
There is little value in repeatedly running all three simply because another month has passed.
Use the symptom to choose the appropriate tool:
Suspected Windows corruption?
DISM, then SFC.
Suspected NTFS/file-system problem?
CHKDSK.
Suspected failing storage?
Back up and investigate the hardware.
Windows remains damaged after DISM/SFC?
Consider Windows 11's repair reinstall or further diagnosis.
That is far more useful than blindly pasting a chain of commands into Terminal and hoping one of them works.
Hamilton Group Can Help With Windows 11 Problems
If Windows 11 keeps crashing, updates repeatedly fail or DISM and SFC report problems they cannot repair, the commands themselves may only be showing you the symptom.
Hamilton Group can investigate Windows corruption, update failures, storage problems, troublesome drivers and wider PC performance issues to determine what is actually causing the fault.
For businesses, we can also help with Microsoft 365, Windows 11 device management, Microsoft Intune, cyber security and ongoing managed IT support.
Need help with a Windows PC that refuses to behave? Call Hamilton Group on 0330 043 0069 or visit hgmssp.com.