Server - MMC GPO Security Options errors - MMC cannot initialize the snap-in

Using MMC snapin, on windows server (in my case on 2016 version), basically managing GPOs, you might face below errors.

I get the error message stated in the subject line whenever I try to open Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> from GPO.

I found three alternatives to manage this error:

Option 1

1. This was broken with the September 8, 2020—KB4577015 update. currently the only solution is to uninstall it.
   
   https://community.spiceworks.com/topic/2291581-windows-2016-mmc-snap-in-error
   
   
2. Then install KB4571694, reboot and try again or patch KB4580346 (I did not investigate at 100%)
   
   https://community.spiceworks.com/topic/2291581-windows-2016-mmc-snap-in-error
   
   https://learn.microsoft.com/en-us/answers/questions/124913/server-2016-mmc-has-detected-an-error-in-a-snap-in
   

Option 2

1. Export REG key:
   
   reg export "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SecEdit\Reg Values\MACHINE/Software/Microsoft/Windows/CurrentVersion/Policies/System/DontDisplayLockedUserId" C:\Temp\DontDisplayLockedUserId.reg
   
   
2. Deleting REG key
   
   reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SecEdit\Reg Values\MACHINE/Software/Microsoft/Windows/CurrentVersion/Policies/System/DontDisplayLockedUserId" /f
   
   
3. Change GPO 
   
   
4. Reimport Register key
   Double clicking here
   C:\Temp\DontDisplayLockedUserId.reg
5. Original article: 
   
   https://learn.microsoft.com/en-us/answers/questions/124913/server-2016-mmc-has-detected-an-error-in-a-snap-in

Option 3

1. On a full patched server or PC install RSAT and solve problem in this way
   https://www.alessandromazzanti.com/2019/05/windows-10-how-to-install-rsat-on.html
   
   
2. Server - How to Execute RSAT snapins with different users without server/client logon necessity
   https://www.alessandromazzanti.com/2017/10/server-how-to-execute-rsat-snapins-with.html
   

REFERENCES

• "The crash can be avoided by deleting the following registry key. Please make sure to export the reg key before deleting anything. Deleting the key will cause the “Interactive logon: Display user information when the session is locked” policy to not appear in the console. (The policy is still effective, but you can’t see it in the UI to edit it). You will need to import the key back later, after the fix has been released.
  
  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SecEdit\Reg Values\MACHINE/Software/Microsoft/Windows/CurrentVersion/Policies/System/DontDisplayLockedUserId"
  
  
• Alternatively follow below article https://learn.microsoft.com/en-us/answers/questions/124913/server-2016-mmc-has-detected-an-error-in-a-snap-in
  
  
• https://community.spiceworks.com/topic/2291581-windows-2016-mmc-snap-in-error