hxxps://support.microsoft.com/en-ca/help/4072699/windows-security-updates-and-antivirus-software It says: ----------------------- Setting the Registry Key Caution Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing keys and values" help topic in Registry Editor (Regedit.exe) or view the "Add and delete information in the registry" and "Edit registry data" help topics in Regedt32.exe. Note: Customers running Windows 8.1 and earlier versions will not receive the January 2018 Windows security updates (or any subsequent Windows security updates) and will not be protected from security vulnerabilities unless and until their antivirus software vendor sets the following registry key: Key="HKEY_LOCAL_MACHINE" Subkey="SOFTWARE\Microsoft\Windows\CurrentVersion\QualityCompat" Value="cadca5fe-87d3-4b96-b7fb-a231484277cc" Type="REG_DWORD” Data="0x00000000” ----------------------------- I use Windows Defender in both 10 and 8.1, do I need to add this key in 8.1?
Windows 10, Windows 8.1, Windows Server 2012 R2 and Windows Server 2016 Customers Microsoft recommends all customers protect their devices by running a compatible and supported antivirus program. Customers can take advantage of built-in antivirus protection, Windows Defender Antivirus, for Windows 8.1 and Windows 10 devices or a compatible third-party antivirus application. The antivirus software must set a registry key as described below in order to receive the latest Windows security updates. So I'm assuming the key isn't required? But I don't know for sure.
If you are using Windows Defender or any other Antivirus program in Windows 8.1 or 10 then that registry key is automatically added to the registry by the antivirus program and Windows Update will allow the latest updates. If Windows Defender is completely disabled and no other antivirus program is enabled, then the registry key will not be set and Windows Update will not offer updates that are dated later than 2017-12. If the registry key is manually set, then Windows Update will offer the latest updates even without an active antivirus program. Summary: If you are using Windows Defender, you will get the latest updates.
I dont use Windefender, but i did add the .reg, using win8.1 and received security updates, as normal.
hmm sorry but I can not agree with this because I just updated Windows 8.1 with 171 updates about 10 minutes ago on another machine I use and as for Windows Defender there is not even a small memory of it because it was removed from the original ISO so I did not have and I do not have any problems ok