Microsoft has begun blocking security patches from computers without antivirus on Windows 7 and Windows 8. There is a registry patch to work around provided below.

But, while we do strongly recommend using an antivirus, it’s especially important to receive security updates if you aren’t using one. To do so, you have to set the same registry key that an antivirus would set, if it were present.

Microsoft’s support site provides the key you need to set. You need to open the Registry Editor and head to the following location (note that if the QualityCompat key isn’t already present, you’ll need to create it inside the CurrentVersion key):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\QualityCompat

Right-click the QualityCompat key, choose New > DWORD (32-Bit) Value, and then give that new value the following name:

cadca5fe-87d3-4b96-b7fb-a231484277cc

Leave the value set to “0x00000000”—its default. You can now close Registry Editor.

Microsoft should rethink this approach for the sake of Windows 7 users. And, if Microsoft is going to prevent these Windows 7 machines from updating, they need to ensure Windows 7 users are better informed about this policy.

More information here:

https://www.howtogeek.com/345946/microsoft-blocks-all-windows-7-security-updates-unless-you-have-antivirus/