For example, the macOS El Capitan already hit the end of life in August 2018 and stopped receiving security updates from Apple.

This new loss of support due to the security certificate only compounds the issues that older Mac users were facing. Why You Should Not Be Running an Outdated Operating System For example, Sophos Home Premium and free antivirus software are also no longer supporting updates for El Capitan, Sierra, and High Sierra operating systems. This loss of support isn’t only for websites, you’ll find that other software providers are also dropping support for those older versions of Mac for a similar reason. These operating system users will notice that websites that used to load do not load any longer because of an outdated certificate. This security certificate has been updated in later versions of macOS, but those older versions have been left out in the cold. Many users running older versions can’t get to secure websites any longer as of the end of September and need to upgrade or purchase a new computer.

This is due to losing the support of an important root security certificate. Users running El Capitan, High Sierra, and older versions of the Mac operating systems have just had access blocked to multiple sites.

Sophos antivirus mac os sierra