Windows Security won't open on Windows 11

[TayDean]

I have tried everything I can think of, I've had two friends who deal with IT problems look at my computer via shared screen with no luck. Since updating to Windows 11 I never noticed Windows Security would not open until recently, it's active and running in the background in Task Manager. I've tried the Powershell and CMD hotfixes, I've reset my PC locally and cloud but I have no restore or recovery points prior to the Windows 11 update. My PC is up to date on all firmware from Microsoft but Windows Security still will not open. Windows Security nor Windows Defender is not listed under my "Installed Apps" or "Default Apps" so I can't try a drop down repair on it. It does show within my Task Manager that there is Windows Defender engine running and in the hidden icons tab it shows Windows Security active. How do you fix this without having to lug your whole PC to a shop?

[#2]

Not quite, though: it still comes back occasionally. Now considering with trepidation the option of an in-place reinstall of W11.

[#3]

@thethoughtgenie  I had the same issues, I tried everything suggested on this thread and several others, and my Windows Security would not open, a blank window would open for just a second, then disappear.  This is what finally fixed it for me.....
 
Step 1. Open Powershell as administrator, run the following command like suggested earlier in the thread...  Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage

Hit enter, close Powershell (If you've done this already, then just go to the next step.) 

Step 2.  Click start on taskbar, in search type... windows security ...DO NOT hit enter though, look to the bottom right of start window, the last option should be... app settings ... click that and it should open a window inside of settings. 

Step 3. Scroll down to the section... Reset ...there's two choices under that "repair" and "reset", click on... repair ....let it do it's thing for a few seconds, and you should be good to go.

If that doesn't work, you can try checking out the rest of the video I got this from, it had 2-3 other options after this one, here is the link.... Windows Security won't open on Win11 solution  

[#4]

@SunshynRFF Yes, this works, and has worked on previous occasions, but the issue keeps coming back...

[#5]

@TayDean 

same problem to me as well, reinstalled windows 2 times now, but the problem keep coming back

[#6]

It works.
Thank you!

[#7]

@KapilAryasolution 4 worked for me. There were files that needed repair, and after that (with a reboot) it works. Thanks

[#8]

I'm in the middle of trying these solutions but when I tried the 2nd one, the command prompt told me it didn't recognize DISM.exe. Is this bad? if so what do I do?

[#9]

Tried them all - none worked

[#10]

@zanhk Rats. Thought I had it licked with the Windows 11 reinstall, but today, after 10 days, the issue coame back.

[#11]

@Mark_Albin How do you run a security scan if Windows Security won't open???

[#12]

Most fixes mentioned here and elsewhere work for a little while, a few days. While it is fixed, you can run a security scan.

[#13]

Can't run a security scan if security center won't open????

[#14]

Need Help here

[#15]

Most fixes mentioned here and elsewhere work for a little while. Run one of the fixes, reboot, and run a security scane while WIndows Security is accessible.

[#16]

@florismkleijne 

[#17]

I got it fixed myself. Thanks

[#18]

How could you fix it?

[#19]

@Junaidgeek1160 windows security troubleshooter does not exist i've looked everywhere

[#20]

Or you need windows defender to be functional for it to open because anything i click on related to windows defender does not open or it just freezes

[#21]

@Mark_Albin 
Sorry Mark, none of your suggestions work !

So, my PC was almost fine, just one update (kb5031358) that wouldn't install by Windows update or downloading it from MS and installing manually, both fail.
MS advice, upgrade in place,..

What terrible advice, it's completely screwed my machine, deleted the HKLM /run list, so my keyboard and mouse don't work, won't let me reinstall them (double click the install exe, nothing happens).
Even tho my profile is Admin, I had to login as Admin to reinstall them).
It reset many of my tweaks that made Win 11 almost useable.
I create a txt file, double click on it and windows says it can't find it !
The Windows Security troubleshooter is no longer there.
I've tried Repairing, and Resetting Windows Security which did nothing.
I'm getting Permission pop-ups, I'm the Admin, I don't need permission to access my own files on my own machine or run programs I own and installed.
It changed ownership of my ALL my partitons and files to 'unknown' or 'NT Authority'.

I built this ne PC just over 3 weeks ago, I've done 10 reformat/fresh installs, and have yet to get to a point where I can actually install my main apps and do some work, but ultimately Win 11 Pro just self distructs.

Obviously I turned off,..
UAC (to stop Windows Nannying),
Memory Interity (otherwise many programs won't install),
Storage Sense (otherwise it will silently delete installed executables (like Skype.exe, Firefox.exe, setpoint.exe, startmenu.exe, and some exe's that stop Avira from working),
and I am Admin !

My anti-malware all works and can't find any malware, this is all stoopid Win 11 Pro (Pro, what a joke).
How could they release this ?
How can they not know how buggy it is ?

I've been building pro PC's for 25 years, this is the worst OS install I've ever done, thank goodness it was for myself and not a client - no wonder people are moving to Mac, MS is actively pushing it's customers away. MS should make a public apology, drop Win 11 and extend support for Win 10 Pro which works flawlessly.