Microsoft’s software repair tool has got an issue; and in an own goal, the source of the problem is Windows Defender.
The sfc/ scannow is a command to run System File Checker, which replaces corrupted Windows files with a cached version.
In a somewhat ironic turn of events, a bug has caused SFC to incorrectly flag Windows Defender PowerShell module files as corrupt.
The bug surfaced after the latest Windows update; and affects almost all versions of Windows 10, including the May 2019 Update, and Windows 10 version 1607.
Microsoft has provided this explanation:
The files for the Windows Defender PowerShell module that are located in %windir%\System32\WindowsPowerShell\v1.0\Modules\Defender ship as part of the Windows image. These files are catalog-signed. However, the manageability component of Windows Defender has a new out-of-band update channel. This channel replaces the original files with updated versions that are signed by using a Microsoft certificate that the Windows operating system trusts. Because of this change, SFC flags the updated files as “Hashes for file member do not match.
While Microsoft are working on a fix, users are advised to ignore the SFC error messages for the incorrectly error-marked files, until the next Windows update is released.
Source and pictures: Windowslatest