After upgrading to Windows 10 Fall Creators Update (Version: 1709, OS Build: 16299.64) mmc.exe is not recognized as a signed file.

  1. I tried to execute it from cmd as administrator and worked:

    c:\Windows\System32\mmc.exe c:\Windows\System32\services.msc

  2. When I'm trying to start the Services app (that is using mmc.exe). enter image description here

    I get the following error

    enter image description here

The file indeed looks like unsigned (but I didn't checked on previous releases). Comparatively other executable file has the tab Digital Signature.

enter image description here

  1. I tried to fix everything by running with no success:

    Dism /Online /Cleanup-Image /RestoreHealth sfc /scannow

There is any solution to fix this?

  • The file properties indicate you have 16299.15 installed but not the build you think is installed – Ramhound Dec 30 '17 at 18:29
  • “I tried to execute it from cmd as administrator and worked:“ So it worked or didn’t work? – Ramhound Dec 30 '17 at 18:31
  • answers.microsoft.com/en-us/windows/forum/windows_7-security/… and other threads indicate your problem is your system no longer trust Microsoft certificates. – Ramhound Dec 30 '17 at 18:34
  • update to 16299.125 and look what happens – magicandre1981 Dec 30 '17 at 19:07
  • c:\Windows\System32\mmc.exe c:\Windows\System32\services.msc worked if executed from cmd as administrator. If I'm going in start menu and search for Services for example I get the errors from screenshots. – raisercostin Dec 30 '17 at 21:44

I reinstalled Windows 10 by keeping my data. There are drawbacks like you need to reinstall some applications. Windows will generate a list with currently installed applications and put it on your desktop Removed Apps.html.

Steps to do it (as explained here https://www.youtube.com/watch?v=5Zkvlcnv-UU )

  1. Boot in Advanced Start-Up
  2. After restart in Advanced Start Up:

    Troubleshoot > Reset this PC (Lets you choose to keep or remove your files, then re-installs Windows) > Keep my files

  3. Save some files from c:\Windows.old\ that contains

    Program Data
    Program Files
    Program Files (x86)
  4. Copy additional data from old profiles from Users/ to new ones.

  5. Reinstall applications found in Desktop > Removed Apps.html
  6. Cleanup old install (https://www.windowscentral.com/how-properly-remove-windowsold-folder-windows-10)

    Win+E > This PC > (right click) > Properties > Disk Cleanup > Clean up system files > Previous Windows installation(s) > Ok > Delete Files > Yes



An 'Administrator' has blocked your access to mmc.exe

This is almost always the cause of Malware/Viruses. Before doing the solution, it is recommended to scan your system using your preferred antivirus.


  1. Find "mmc.exe"; it is located here: "C:\Windows\System32"

  2. Right-click the executable then click Properties in the drop-down menu. A window should appear.

  3. In the window, click the Security tab.

  4. In this tab, there will be a button called Advanced. Click it. A second window should appear.

  5. In this window, there will be a hyperlink called Change accompanied by a UAC Shield (Blue/Yellow). Click it. A third window should appear.

  6. The box accompanied by the text Enter the object name to select (examples): should be there. In it, you should write your account's name. For example, if I set up my account with the name: John Doe, I would type in 'John'.

  7. After you have written your name, click the button named Ok. If all has gone well, the third window should disappear. The second window's Owner should be your account name.

  8. Now click the Ok button. The second window should close.

  9. Click the Advanced button again. The second window should appear again.

  10. There will be a button called Change Permissions accompanied with the UAC Shield. Click it. The same window should refresh itself.

  11. There should be a button called Add. Click it. A fourth window should appear.

  12. In the fourth window, there should be a hyperlink called Select a principal. Click it. A fifth window similar to the third window should appear.

  13. Fill the window like you did in Step 6, then click Ok. The fifth window should close.

  14. The fourth window's checkboxes should no-longer be greyed out. Now check the Full Control checkbox. All the boxes should now appear checked.

  15. Click the Ok button.

There will be a warning reminding you that The security of your computer will be reduced. mmc.exe naturally needs administrator permissions to run. You will be able to rectify any viruses easily. Click OK on the warning. The fourth window should now close.

  1. Now click the Ok button for all subsequent windows. (Second, First windows)

Now try runing mmc.exe without administrator permissions.

Side Notes

mmc.exe is NOT signed on my system either. Mabye it's not meant to be signed?

  • What you are doing here is changing the ownership of mmc.exe to you. However, this is a hack, not a fix as members of the Administration group already have read & execute permissions. – HDave Sep 13 '18 at 14:55
  • Not really a hack, just reverting default settings. It's possible that a program or someone else has changed the settings of the group Administrator. – Ultrasonic54321 Sep 13 '18 at 17:06

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