Microsoft fixes the Windows Defender sfc bug (August 2019)

[English]Microsoft has just fixed the error caused by Defender when executing the command sfc /scannow. Here is some information on this topic.


Since July 2019 all Windows versions are affected by a problem. It is no longer possible to run a system file check for corrupted files.

File system checker sfc bug since July 2019

Under Windows, an administrative prompt can be used to check the system for corrupted files. To do this, simply use the command:

sfc /scannow

is executed. If the command finds corrupted files, the System File Checker (sfc) should be able to repair them. However, it happens again and again that this repair cannot be carried out.

This is exactly the case with sfc, which finds corrupted files after installing the July 2019 updates in Windows, but cannot repair them. However, it turned out that it had nothing to do with the July 2019 updates. Rather, analysis showed that a broken Defender signature file was responsible for the failed system file check. I had reported it in the blog post Windows: July 9, 2019 Updates breaks sfc. Later Microsoft admitted a with with sfc (see Microsoft confirms July 9, 2019 Updates breaks sfc in Windows).


Microsoft fixed the issue

Microsoft has published the support articleSystem File Checker (SFC) incorrectly flags Windows Defender PowerShell module files as corrupted on August 17, 2019. They wrote:

The System File Checker (SFC) tool flags files that are located in the %windir%\System32\WindowsPowerShell\v1.0\Modules\Defender folder as corrupted or damaged. When this issue occurs, you see error entries that resemble the following:

Hashes for file member do not match.

Microsoft had already admitted that this was a known issue in Windows 10, version 1607 and later versions. It occurs in Windows Defender version 4.18.1906.3 and later versions.

The issue has been fixed by updating Windows Defender to version 4.18.1908. After you install this update, PowerShell files that are part of Windows are no longer reported as incorrect by sfc /scannow.

Note: Currently it seems, that Microsoft not have released Windows Defender version 4.18.1908 yet.

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3 Responses to Microsoft fixes the Windows Defender sfc bug (August 2019)

  1. Akuma says:

    Am I the only one that is seeing that Microsoft support and in general the Microsoft work is going down the hill and without brakes but faster as the time passes?
    I can see it on Windows 10 new bugs, Windows 10 stupid regression bugs, Windows 10 Appx, Windows 10 GPO templates, Windows 10 Updates, etc.

    It's cristal clear now for me that the retirement by age, of the Microsoft Team that produced Windows XP has had a inmense impact on everything related to Windows Microsoft is doing.


  2. Ralph Griffith says:

    'cristal' clear – is there such a word?

  3. Klaus says:

    'crystal clear' = Unambiguous; easily understood ( powered by Oxford)

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