Working Fix/Solution :
According to https://www.windows11forums.com/threads/windows-11-defender-firewall-will-not-load.355/
The cause of the broken firewall (and broken Microsoft Store due to the firewall is broken) is because the value of this specific key is corrupted:
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\mpssvc\Parameters\AppCs
Key DebugedLoopbackApps
It could be corrupted while in Windows 10 before the upgrade to 11. Or corrupted as 11.
The reason why it is broken is unclear, but it seems upgrade from windows 10 to 11 is a possible cause.
The fix:
to fix this key, a normal user has no permssion to edit this key.
And it seems the normal user can not take ownership of the key either.
The easy solution is to use psexec/psexec64 from system internal suite.
Download that.
Open cmd as admin, run this :
psexec64.exe -s -i cmd.exe then run regedit.exe
or just
psexec64.exe -s -i regedit.exe
Navigate to the key, right click on AppCs folder, select permission,
change SYSTEM user's permission to Full Controll.
Delete the key DebugedLoopbackApps , then recreate it without setting value.
Reboot the system.
Then the firewall should have been back to business.
MS Store should also be happy now.
Your Paint, Caculator, Notepad etc should have also been good for running or install or upgrade.
Things we learnt:
The Windows team for win 10/11 is now only doing damage to the existing system.
The Microsoft Store is so bad. It depends on the firewall to function. And your built in apps depending on the MS Store to function.
In another thought,
DO NOT MOVE YOUR CMD.EXE to Microsoft Store, as doing that might leave no room to fix the issue.
I thought I need a local account password in the process. Tried to set local account password,
Reset your Windows local account password
click that link in the new settings program, it only opens a search result with
how to set local account password site:microsoft.com
what a joke are you doing.
And when the user as a PIN as sign in, in the settings program or somewhere it says you shall click PIN sign in issue on the sign in screen to create local account password, but there's just no PIN sign in issue to be clicked on the sign in screen.
The new settings program: super slow and fail a lot.
The PIN sign in part: very confusion and does not work with the old password idea.
Force the user to use live account instead of local password: same as above.
Microsoft Store: Dont like it at all, winget is a great thing though.
Moved paint, caculator, notepad etc to MS Store: not good idea, they wont work when MS Store or firewall is broken..
The MS Store needs to depending on the firewall to functional: Not good idea. .
By the way, in the new settings program, when I click Accounts -sign in options, it usually takes like minutes, several minutes to response. What a thing.
I just want to say I spent five hours with a completely borked W11 upgrade before finding this post. This fixed my problem in it's entirety. I ran across many waylaid travelers that sound like they're having this exact issue and have no idea what's causing it, all of which gave up. This is the only place I found a working fix. I chased the initial problem down through CPU utilization which gave me a hunch to google windows 11 firewall and the 0x errors that randomly pop up on all programs and anything I tried to do. I can only imagine how many people had to do fresh installs from this, as the symptoms are so absolutely random and unrelated. Some people even mentioned that repair installations/reinstalling didn't even fix it.
This is absolutely absurd and I tried literally everything. I'm currently covered in the blood from a goat I sacrificed and have a alter to bill gates... he still didn't reply. Trash firewall that literally went berserk.