Windows 7 computers that do not use compatible antivirus software no longer receive security updates from Microsoft because of a compatibility issue that is thought to be causing blue screens.
This policy was first introduced in Windows 10 with the January 2018 cumulative updates. Microsoft asked Windows 10 systems with incompatible antivirus software to set a special registry key to continue receiving security updates as the company prevented updates from circulating.
According to Myce, systems running Windows 7 without antivirus or with security products that are not considered compatible will also be excluded from receiving security updates.
Unlike Windows 10, Windows 7 does not come with a built-in security program, so Microsoft offers Microsoft Security Essentials for free to those who have not yet upgraded to the latest version of the operating system.
To set the registry key that Microsoft checks when it sends new updates, you must go to the following path and then create a new DWORD (32 bit) entry and name it cadca5fe-87d3-4b96-b7fb-a231484277cc with a value of 0 :
Computer \ HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ QualityCompat
As for the list of security products that may not be supported (not considered compatible) and thus prevent Windows 7 systems from receiving updates, Microsoft itself does not provide any guidance on this issue.
However, most major antivirus companies have already updated their software to comply with the new Windows 10 policy and chances are the same is true for Windows 7, so the majority of antivirus products should be technically compatible with the 2009 operating system.
Windows 7 will continue to receive updates until January 2020 and it is critical for systems that are still running this version of the operating system to be updated with the latest patches.