Microsoft have determined that your computer must have antivirus compatible with their new Spectre/Meltdown security patch. If you do not have the correct antivirus installed (and this includes having no antivirus) Windows Update will cease to function as of this month.
That’s right if you do not have the registry setting below you will not be getting any windows updates.
Windows 10, Windows 8.1, Windows Server 2012 R2 and Windows Server 2016
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 January 2018 security updates.
Windows 7 SP1 and Windows Server 2008 R2 SP1 Customers
In a default installation of Windows 7 SP1 or Windows Server 2008 R2 SP1, customers will not have an antivirus application installed by default. In these situations, Microsoft recommends installing a compatible and supported antivirus application such as Microsoft Security Essentials or a third-party anti-virus application. The anti-virus software must set a registry key as described below in order to receive the January 2018 security updates.
Customers without Antivirus
In cases where customers can’t install or run antivirus software, Microsoft recommends manually setting the registry key as described below in order to receive the January 2018 security updates.
Setting the Registry Key
Customers will not receive the January 2018 security updates (or any subsequent security updates) and will not be protected from security vulnerabilities unless their antivirus software vendor sets the following registry key: