Look, Windows Defender is great, but it can’t fix everything. That’s why there are other anti-malware apps out there that work great with it, like free downloads Microsoft Security Essentials and Malwarebytes Anti-Malware. (When you’re done here, check out our “How to protect your PC” page for more.) If you’ve recently updated Windows Defender and you’re getting an error message saying that there’s a problem with the built-in firewall, don’t worry. This is a common problem that can be easily fixed.
Windows Defender error code 0x80016CFA is a common Windows Defender error among Windows 10 users. Windows Defender error code 0x80016CFA usually appears when you try to open Windows Defender or in the Event Viewer log. Windows Defender error code 0x80016CFA occurs when the Windows Update Agent Auto-Restart feature is enabled on Windows 10 systems and the Windows Defender service crashes.