Windows Defender Firewall can't start after system rescue, access is denied, error code 0x8007045b

Question

Windows 10 Version 21H2 (OS Build 19044.1682)

My Windows 10 networking stack was recently corrupted, which I fixed by reinstalling Win10 from a USB device.

Everything appears to be working fine now except that Windows Defender Firewall can't start.

Event Viewer repeatedly reports:

The Windows Defender Firewall service terminated with the following service-specific error:
Access is denied.

When I select "use recommended settings" (or "restore default settings") under the Windows Defender Firewall control panel, I get:

Windows Defender Firewall can't change some of your settings. Error code 0x8007045b.

I've tried using the Troubleshooter here: https://support.microsoft.com/en-us/windows/automatically-diagnose-and-fix-problems-with-windows-firewall-513e9cf8-19ae-d579-2092-d5e64fe06f5f . Sometimes it says it can't find a problem, sometimes it says it's fixed the problem, but in either case it doesn't actually fix the problem.

I've tried booting into safe mode.

I've tried sfc /scannow and dism /online /restorehealth as well as all of the suggestions here https://answers.microsoft.com/en-us/windows/forum/all/windows-defender-firewall/5c8fce55-8e94-4545-868e-acfe3523ff14

I believe the Defender Firewall failure is preventing me from being able to preview documents in Outlook, as noted here https://learn.microsoft.com/en-us/answers/questions/836899/unable-to-preview-any-ms-office-documents-in-outlo.html

Any ideas how to troubleshoot/fix?

Answer 1

Found a solution. I had to go to HKLM\System\CurrentControlSet\Services\BFE in regedit and add 'local service', 'network service' and 'nt service\bfe' all to the security list with at least modify permissions and set those permissions to be recursive for all the keys under BFE. Now Windows Defender finally works again, as do Outlook document previews.