SFC /Scannow Not Working? How to Fix It

When sfc /scannow does not work, the next step depends on how it fails.

SFC can:

• refuse to start
• stop at a percentage
• report that Windows Resource Protection could not perform the requested operation
• find corrupt files but fail to repair them
• finish normally even though the original Windows problem remains

Those results do not all have the same cause.

Microsoft currently recommends running DISM before SFC when repairing Windows system corruption because DISM repairs the Windows component store that SFC can use as a repair source.

Start with that supported sequence, then follow the branch that matches your result.

Run DISM Before Repeating SFC

Open Command Prompt (Admin) or Terminal (Admin).

Run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

Let it finish completely.

Then restart Windows.

Open an elevated command window again and run:

sfc /scannow

Do not close the window before verification reaches 100%.

Microsoft currently recommends this order:

DISM → SFC

If SFC now completes successfully, read the final message before doing anything else.

If SFC Says You Must Be an Administrator

SFC needs an elevated command window for a normal repair scan.

Open Start, search for:

cmd

Right-click Command Prompt and choose:

Run as administrator

Then run:

sfc /scannow

If the title bar does not indicate an administrator session, close the window and reopen it correctly.

This is not a system-corruption problem if SFC works as soon as it receives the required permissions.

If SFC Appears Stuck at a Percentage

SFC can remain at the same percentage for a while without actually being frozen.

Do not immediately close the window because it sits at 20%, 40%, 73%, or another value.

Watch for signs that the computer is still active, such as:

• disk activity
• CPU activity
• the Command Prompt process continuing to use resources

If the scan eventually moves, let it finish.

If it repeatedly stops at the same percentage on separate attempts, do not keep interrupting and rerunning it.

Instead:

1. Run DISM.
2. Restart Windows.
3. Run SFC again.
4. Check the system drive if the same stall returns.
5. Try Safe Mode if normal Windows continues to interfere.

A repeated stall at the same point is more meaningful than one slow scan.

If Windows Resource Protection Could Not Perform the Requested Operation

This is a specific SFC result:

Windows Resource Protection could not perform the requested operation

Microsoft recommends running SFC in Safe Mode for this condition.

Boot into Safe Mode through:

Settings > System > Recovery > Advanced startup > Restart now

Then choose:

Troubleshoot > Advanced options > Startup Settings > Restart

Press:

4

or:

F4

for Safe Mode.

Once Windows starts, open Command Prompt as administrator and run:

sfc /scannow

Microsoft also says the following folders should exist:

%WinDir%\WinSxS\Temp\PendingDeletes

and:

%WinDir%\WinSxS\Temp\PendingRenames

For a focused repair path for this exact error, use Windows Resource Protection Error: How to Fix It.

If SFC Found Corrupt Files but Could Not Repair Them

You may see:

Windows Resource Protection found corrupt files but was unable to fix some of them.

First make sure DISM has already completed successfully.

Run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

Restart Windows.

Then run:

sfc /scannow

again.

If SFC still cannot repair the same files, inspect the SFC entries from the CBS log.

Use:

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

Windows creates:

sfcdetails.txt

on the desktop.

Microsoft notes that this file can contain entries from multiple SFC runs, so use the date and time to identify the latest scan.

Do not replace Windows system files manually unless you know exactly which file is damaged and have a valid matching replacement.

If DISM Fails Too

An SFC failure becomes a different problem when:

DISM /Online /Cleanup-Image /RestoreHealth

also fails.

DISM normally uses Windows Update as a repair source.

If Windows Update cannot provide the required files, Microsoft supports specifying another valid repair source.

A general command format is:

DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows /LimitAccess

The example path must be replaced with a valid repair source appropriate for the Windows installation.

Do not point DISM to a random Windows folder downloaded from the internet.

If DISM returns a specific error code, troubleshoot that code rather than repeatedly running the same RestoreHealth command.

For example, see DISM Error 0x800f0915: How to Repair the Source Problem if that is the result you receive.

Check the System Drive When SFC Keeps Failing at the Same Point

SFC depends on reliable access to protected Windows files.

File-system errors can interfere with the scan.

Start with a non-disruptive check:

chkdsk C: /scan

If Windows reports file-system errors that require repair, follow the recommended CHKDSK action.

I prefer /scan as the initial check rather than immediately scheduling a long /r operation.

Pay more attention to the drive when you also notice:

• repeated file corruption
• freezing during file access
• storage-related blue screens
• SMART or manufacturer diagnostic warnings
• an SSD disappearing intermittently
• unusual sounds from a mechanical hard drive

Back up important data before aggressive repair attempts if the storage device may be failing.

If SFC Works in Safe Mode but Not Normal Windows

That result is useful.

It suggests SFC itself can work, while something loaded during a normal startup may be interfering.

A clean boot can help isolate that conflict.

Press:

Windows + R

Enter:

msconfig

Under Services:

1. Select Hide all Microsoft services.
2. Disable the remaining third-party services.
3. Open the Startup tab.
4. Open Task Manager.
5. Disable nonessential startup applications.
6. Restart Windows.

Run:

sfc /scannow

again.

If SFC now completes, re-enable third-party items gradually until the conflict returns.

Restore the normal startup configuration after testing.

Check Windows Modules Installer Only If It Was Disabled

Windows Modules Installer, also called TrustedInstaller, supports Windows servicing.

Press:

Windows + R

Enter:

services.msc

Find:

Windows Modules Installer

Its normal startup type is typically Manual.

If an optimization tool or manual tweak disabled it, return it to Manual.

Do not change unrelated Windows services or force everything to Automatic simply because SFC failed.

If Windows Update Is Waiting for a Restart

Complete pending Windows updates before continuing with repeated repair scans.

Open:

Settings > Windows Update

Install available updates.

Restart when Windows requests it.

Then run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

followed by:

sfc /scannow

Pending servicing operations can complicate system repair, so clearing the normal update/restart cycle is a sensible step.

Run SFC Offline When Normal Windows Cannot Complete the Scan

Offline SFC is useful when:

• Windows cannot boot normally
• normal SFC repeatedly fails
• protected files may be locked
• you are already working from Windows Recovery Environment

Open:

Troubleshoot > Advanced options > Command Prompt

Do not assume Windows is still on C:.

Test likely drive letters:

dir C:\Windows
dir D:\Windows
dir E:\Windows

Identify the partition containing the real Windows installation.

If Windows is on D:, an offline scan can use:

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

Replace D: with the actual drive letter on your PC.

Microsoft documents /offbootdir and /offwindir specifically for offline SFC repair.

If SFC Completes but Windows Is Still Broken

A clean SFC result does not mean every Windows problem is caused by something SFC can repair.

This message:

Windows Resource Protection did not find any integrity violations.

only means SFC did not detect corruption in the protected system files it checked.

Your original problem may still be caused by:

• a driver
• an application
• a user profile
• Windows Update
• a service
• hardware
• storage
• network configuration
• a damaged component outside SFC’s repair scope

Do not keep running SFC because another Windows feature remains broken.

Troubleshoot the actual symptom instead.

When a Windows Repair Reinstall Makes More Sense

If DISM, SFC, Safe Mode, offline SFC, and disk checks all fail to produce a stable Windows installation, continuing to cycle through commands is rarely useful.

Windows 11 provides a repair option under:

Settings > System > Recovery

On supported systems, you may see:

Fix problems using Windows Update > Reinstall now

This reinstalls the current version of Windows while preserving apps, files, and settings.

For the full process, see Reinstall Your Current Version of Windows to Repair System Files.

That is a more appropriate escalation than repeatedly running SFC when the underlying Windows servicing environment itself is damaged.

What the Main SFC Results Mean

Windows Resource Protection did not find any integrity violations

No corruption was detected in the protected system files SFC checked.

Windows Resource Protection found corrupt files and successfully repaired them

Restart Windows and test the original problem.

Windows Resource Protection found corrupt files but was unable to fix some of them

Run DISM, then SFC again. If the same files remain unresolved, review the CBS details.

Windows Resource Protection could not perform the requested operation

Run SFC in Safe Mode and follow the dedicated Windows Resource Protection troubleshooting path.

The important part is to stop treating every SFC failure as the same problem. Run DISM first, read the exact SFC result, and only then choose Safe Mode, CBS log analysis, disk checks, offline repair, or a broader Windows repair.