Windows 10: Windows Defender Firewall not running, can't turn on on Windows 11

Windows Defender Firewall isn't running and I can't turn it on. It has error code 0x45B when I try to open it, in the security setting it says it's not available and everything I can find on the net has not worked. I've tried every fix I can find here on Microsoft's pages for this, other tech sites, ran the DISM and SFC, Windows Updater troubleshooter, tried repairing using the Windows ISO file from Microsoft which fixed the problem for a day then it stopped working again, reset the firewall with the command prompt and absolutely nothing has fixed the issue. I'm now left with doing a clea

:)

 

windows defender firewall

Hi Faye,

Third-party antivirus programs usually have their own uninstallers provided by the software developer. We suggest checking the developer's website or contacting their support team for assistance with uninstalling their program. After fully uninstalling the
third-party antivirus software, you may turn on Windows Defender by following these steps:

• Click Start.
• Type Windows Defender Security Center and press Enter.
• Click Firewall and network protection.
• Click Private (discoverable) network and click On.
• Click Public (non-discoverable) network and click On.

Let us know if you have any other concerns about Windows Defender.

 

Windows Defender Firewall showing On and Off at the same time

Hi Jerry,



Thank you for writing to Microsoft Community Forums.



I understand that the Windows Firewall shows as switched off even after turning it on. For better understanding of the issue, please answer the questions below.

1. Which build version of Windows are you using currently?
   
2. Are you aware of any changes being made to the PC?
   
3. Do you have any security software/firewall installed?
   

Meanwhile, I would suggest you to follow the steps mentioned below and check if that helps.



Method 1:



I would suggest you to run the troubleshooter for Windows Firewall and check if that helps. Refer the article

Automatically diagnose and fix problems with Windows Firewall



If the above method doesn’t t work, please follow the next method.



Method 2:



I would suggest you to try enabling the services responsible for Windows Firewall and check if that helps.

1. Press Windows key + R. This will open
   Run. Alternatively, you can go to Start and search for ‘Run’.
   
2. In Run dialog box, type services.msc and hit enter.
   
3. Now look for the services: Security Center,
   Windows Defender Antivirus Service, Windows Defender Firewall Service,
   Windows Defender Advanced Thread Protection Service,
   and Windows Defender Antivirus Network Inspection Service.
   
4. Right click on each service and click on Start.
   

If the above method doesn’t work, please try the next method.



Method 3:



I would suggest you to check if any conflicting registry entries are present which are blocking Windows Defender Firewall to turn on.



Note: Important this section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow
these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs.



Refer the article on
How to back up and restore the registry in Windows

1. Press Windows key + R. This will open
   Run. Alternatively, you can go to Start and search for ‘Run’.
   
2. In Run dialog box, type regedit and hit enter.
   
3. Now navigate to the location: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
   
4. Look if there are any registry keys named: MSASCui.exe, MpCmdRun.exe or MsMpEng.exe.
   
5. If there are any such entries, then delete them by right clicking and selecting Delete.
   
6. Click on Yes.
   
7. Restart the PC.
   

If the issue persists, please get back to us with the results of troubleshooting steps to assist you further.



Regards,

Prakhar Khare

Microsoft Community – Moderator

 

Windows 10 Defender Firewall can't be turned off

You can turn off and reset Windows Defender Firewall from:

1. Open Control Panel.
2. Click on System and Security.
3. Click on Windows Firewall.