Fix Windows Defender Error Code 0x80016CFA



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Error code “0x80016CFA” is one of many Windows Defender related tech support scams. This scam typically uses Microsoft Edge web browsers and targets computers running Microsoft Windows 10, but is not limited to Windows 10. It usually appears on your system a few days after downloading third-party software such as a media player, download manager or PDF converter.

This bogus warning is triggered by adware plugins that are distributed as third-party software attachments. When you see this fake warning, your web browser appears in full screen mode and hangs, so you cannot exit the blue screen environment by pressing the “X” or “OK” button. The message contains several error check values, such as 0x80060402, 0x0000007B and 0x80060402.

It also contains the BSOD error name “INACCESSIBLE_BOOT_DEVICE” and the file name “dllRegisterSetting”. This technical information refers to existing Windows errors. If you type any of these codes into a Google search, you will get plenty of information. When a user falls into the trap, scammers call the number of a specific “certified Windows technician.” That’s where the danger lies.

The number listed does not belong to any IT professional, at least not a verified professional. This scam is trying to scam people out of money or get them to remotely get full control over their computers. If you get error code 0x80016CFA and a phone number to call, never try to call them. Update your antivirus and perform a full system scan.

Remove suspicious applications.

  • First of all, you need to access the control panel.
  • Then select “Uninstall a program” under “Programs” and check the list of programs installed on your computer.
  • You simply uninstall all suspicious or unwanted programs.

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Remove a third-party antivirus program

Most importantly. Because of system conflicts, only one anti-malware tool can currently be activated. In fact, the dual presence of antivirus programs, with both running in the background and providing real-time protection, is not an issue. So we have to make a choice. Whether you use your own anti-malware tool or use a third-party alternative instead.

While most antivirus solutions disable Windows Defender during installation, some may not. So if you’ve made a decision and, for example, BitDefender has just been installed, remember to turn off Windows Defender afterwards.

Here’s how it works, following a few simple steps:

  • Open Windows Protector from the notification area or use the search bar.
  • Select Virus and Threat Protection.
  • Open the virus and threat protection settings.
  • Turn off real-time and cloud-based protection.
  • Quit Windows Defender Center and turn on your third-party antivirus again.

Check the Windows Defender service

You can’t remove the Windows Defender from Windows 10. You can disable it (as described above), but the dedicated service will still run in the background. Unless stopped manually or by a third-party antivirus. This service is, in many cases, the likely cause of a Windows Defender error. The dedicated service should always run in the background and run automatically from the system shell. Especially if you use Windows Defender for real-time protection or scheduled scans.

For some reason, the Windows Defender service is often disabled. Some third-party tools limit this. However, if you only use Windows Defender to protect your system, it should always be on.

That’s why we recommend that you consult a dedicated Windows Defender service.

  • Uninstall third-party antivirus and restart your computer.
  • Press the Windows + R key to open the “Run” command prompt with elevated privileges.
  • At the command prompt, type services.msc and press Enter.
  • Scroll down until you get to the Windows Defender antivirus service.
  • It should run automatically (it’s required), but you can switch it to manual mode because of an encounter with an alternate tool. If so, right-click it and open “Properties”.
  • Set the startup type to Automatic and confirm the changes.
  • Reboot your computer.

In-depth analysis with Malwarebytes

After you’ve successfully removed all traces of adware from your browser, the final step is to make sure you’ve cleaned up any remaining adware files to make sure your system can’t be infected again.

There are several tools that can help you. However, we recommend Malwarebytes. This is a powerful on-demand scanner that is known to remove most of the malware, adware and malicious code that may have infected your browser.

If you decide to use this tool, you should perform a deep scan instead of a quick scan to improve the volume of the procedure. It will take longer, but the result will be better.

Once the scan is complete, restart your computer one last time and open the same browser that previously generated error code 0x80016CFA. You should not have the same problems anymore.



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