How to Fix Windows Defender Firewall Problems in Windows 10

Windows 10 shows so many notifications in the taskbar that I have started to ignore them for the most part. But sometimes, some scary looking notifications catches your attention. Recently, Windows 10 notified me that Windows Defender Firewall was unable to run (it was previously called just Windows Firewall).

So I quickly launched the services manager (launch the Run dialog (Win+R), type services.msc and press Enter) and found that the Windows Defender Firewall was listed there as usual but its startup type was set to “manual”. I tried to run it by selecting it and pressing the small “run” button in the toolbar. But now I was shown another error – “Security and Maintenance cannot turn on Windows Firewall” with the details  hinting about error code 5.

Fix Windows Defender Firewall

Fortunately, Microsoft has made fixing all the Windows Defender Firewall related problems very easy. Here is how you can quickly fix the problems when Windows Defender Firewall is refusing to start in your PC:

  1. Download Windows Defender Firewall troubleshooter from
  2. Double-click on the downloaded troubleshooter file WindowsFirewall.diagcab.Fix Windows Defender Firewall
  3. Click on the Next button in the Windows Firewall Troubleshooter window.
  4. The troubleshooter will run a number of scripts on your PC. It will add the missing registry entries, it will fix the permissions and it will check for the missing files. After this it will attempt to start Windows Defender Firewall. In the end you will be shown a summary of the result. At this point, you can click on the Close button to close the troubleshooter.Fix Windows Defender Firewall

If this tool does not fix your Windows Defender Firewall problem, then you have two choices – you can restore your PC from backups or System Restore points to an earlier time when Windows Defender Firewall was working without any problems, or you can try installing some third-party firewall like Comodo Free Firewall.