What does 'found corrupt files but unable to fix' mean?

SFC found damaged files but the repair source (WinSxS) is also damaged. Run DISM first to fix the source, then retry SFC.

Where do I find the SFC log?

The detailed log is at C:\Windows\Logs\CBS\CBS.log. Search for '[SR]' entries to see what was checked and repaired.

Windows SFC /scannow Errors — System File Checker Troubleshooting

Errorsystem

Overview

Complete guide to Windows SFC /scannow errors including 'could not perform the requested operation', 'found corrupt files but unable to fix', and pending repairs.

Key Details

SFC (System File Checker) scans and repairs protected Windows system files
Common result: 'Windows Resource Protection found corrupt files but was unable to fix some of them'
SFC logs results to %WinDir%\Logs\CBS\CBS.log
SFC requires the Windows component store (WinSxS) to be healthy for repairs
Must be run from elevated (Administrator) Command Prompt

Common Causes

Corrupted Windows component store (WinSxS folder) — SFC needs healthy sources to repair from
Windows Update failed installation leaving system files in inconsistent state
Malware that modified protected system files
Third-party software replacing system DLLs with modified versions
Disk errors corrupting system files on the Windows partition

Steps

1Run DISM first: DISM /Online /Cleanup-Image /RestoreHealth (fixes the component store SFC uses)
2After DISM completes, run sfc /scannow again from elevated Command Prompt
3If DISM fails, specify a Windows ISO as source: DISM /Online /Cleanup-Image /RestoreHealth /Source:D:\sources\install.wim
4Check CBS.log for specific files that failed: findstr /c:"[SR] Cannot" %WinDir%\Logs\CBS\CBS.log
5As last resort, run SFC from Windows Recovery: sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows