No, I get the same message. Graphically it looks a bit different, presumably due to different Windows 10 versions, but the same content.
I'm not sure if the elevated shortcut would work because I never try to start MMC directly. It gets called by other programs. Someone suggested (with instructions!) somewhere else that I try removing the catroot2 folder. I'll give this a try once I've reassured myself that it's a safe thing to do.
@ricecrispies
Your statement above....
Try to start it yourself. See what happens. It is only a shell for the Microsoft Management Console.
In the search at bottom left of taskbar (Cortana box), type MMC. First choice at top of results box should be
Click that choice. You should get
It doesn't do anything by itself, it's only a shell. It needs "snap-ins" added to it in order to actually do something. Event Viewer is an example of a MMC with a snap-in for viewing system logged events.
If you can get to this, then your other "programs" that are calling MMC don't have the privilege to run it.
Be cautious deleting Catroot or Catroot2. They are used by Windows Update. More info here: How do I Delete all contents of catroot2 folder but leave the catroot2 - Microsoft Community
Finally got around to trying deleting catroot2 today and .................
............. it didn't work
Thanks for your suggestions. I tried running mmc directly, but I got the same error. And I tried deleting catroot2 and rebooting, but that made no difference either. There was one untoward thing when I was deleting catroot2: when I tried to stop wuauserv I got told that it couldn't be stopped. I assumed that this meant that it was already dead, but could it have still been running and interfered with what I was doing?
Since it can't verify the security certificate, it's possible that the Windows Registry has gotten corrupt somehow.
You may need to backup all of your personal and important files and do a clean install of Windows
It's odd that the system file "MMC.exe" is being blocked like this. You might run a SFC /SCANNOW command to see if the file may be corrupted. Afterwards, try opening it again.
Check, if you have any untrusted certificates.
But in order to access them, you need to open mmc.
You need to enable system admin and then login into that account.
Enable or Disable Elevated Administrator account in Windows 10 Windows 10 User Accounts Tutorials
Then run CMD as admin and run mmc. Expand untrusted certificates only and remove, if any.
Delete Untrusted Root CA Certificates
Antiviruses tend to install theirs certificates and mess up system, it might be worth uninstalling any AV.
I get how to delete the untrusted certificates, but how do I work out which ones I shouldn't trust?
Check, if you have any untrusted certificates.
But in order to access them, you need to open mmc.
You need to enable system admin and then login into that account.
Enable or Disable Elevated Administrator account in Windows 10 Windows 10 User Accounts Tutorials
Then run CMD as admin and run mmc. Expand untrusted certificates only and remove, if any.
Delete Untrusted Root CA Certificates
Antiviruses tend to install theirs certificates and mess up system, it might be worth uninstalling any AV.
I've already run sfc /scannow. It said there were some things it couldn't correct and to look in a ludicrously long and non-self-explanatory log file to find out what they were.
If you haven't already, run the Dism /Online /Cleanup-Image /RestoreHealth command to repair any component store corruption, restart the PC afterwards, and try the sfc /scannow command again.
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