Source: Chris Hoffman, HowToGeek.ca, March 15, 2018
Microsoft is now withholding security updates from Windows 7 users who don’t have an antivirus installed.
There’s a way around this limitation, but you have to manually set a registry key.
This is all thanks to the patch for Meltdown and Spectre that rolled out via Windows Update. Microsoft noticed that many antivirus applications were incompatible with the update and caused blue screen errors.