Can’t Open Device Manager or any MMC applet

In Windows 10 or Windows 11. when you try to Device Manager from the Command Prompt (admin) window, the Device Manager doesn’t run. The following error message comes up when you do so:

C:\windows\system32\devmgmt.msc

This file does not have an app associated with it for performing this action. Please install an app or, if one is already installed, create an association in the Default Apps Settings page.

(and)

The system cannot execute the specified program

(or)

Restrictions

This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator.

Right-clicking on the Start button (or pressing Win + X) and Choosing “Device Manager”, or right-clicking on This PC and clicking “Manage” gives the same result.

The same error occurs when you attempt to open Disk Management, Computer Management, or any other MMC console.

Cause

Cause 1

The above error can occur if the .msc file association is broken. However, as a workaround, you can launch Device Manager or Computer Management by running one of the following commands from Command Prompt:

mmc.exe devmgmt.msc

%SystemRoot%\system32\mmc.exe %SystemRoot%\system32\devmgmt.msc

mmc.exe compmgmt.msc

%SystemRoot%\system32\mmc.exe %SystemRoot%\system32\compmgmt.msc

But the following canonical Control Panel command-line does not work:

control.exe /name Microsoft.DeviceManager

Cause 2

Another possibility is that mmc.exe is blocked using group policy or registry-based policy (“DisallowRun“) settings. In that case, the above commands don’t help.

The DisallowRun registry key corresponds to the Don’t run specified Windows applications GPO.

Resolution

To resolve the file association or restrictions error when opening an MMC applet, follow these steps:

1. Download mscfix.reg (zipped)
2. Unzip the archive and run mscfix.reg
3. Click Yes to confirm.
4. Click OK.

This fixes the .msc file association on your Windows 10 or 11 computer.

INFO: Contents of mscfix.reg

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.msc]
@="MSCFile"

[-HKEY_CLASSES_ROOT\mscfile]

[HKEY_CLASSES_ROOT\mscfile]
@="Microsoft Common Console Document"
"EditFlags"=dword:00100000
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
  00,6f,00,6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
  32,00,5c,00,6d,00,6d,00,63,00,62,00,61,00,73,00,65,00,2e,00,64,00,6c,00,6c,\
  00,2c,00,2d,00,31,00,33,00,30,00,00,00

[HKEY_CLASSES_ROOT\mscfile\DefaultIcon]
@="%1"

[HKEY_CLASSES_ROOT\mscfile\shell\Author]
@="&Author"
"MUIVerb"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,\
  6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,\
  00,6d,00,6d,00,63,00,62,00,61,00,73,00,65,00,2e,00,64,00,6c,00,6c,00,2c,00,\
  2d,00,31,00,33,00,33,00,35,00,31,00,00,00

[HKEY_CLASSES_ROOT\mscfile\shell\Author\command]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
  00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,00,6d,00,\
  63,00,2e,00,65,00,78,00,65,00,20,00,2f,00,61,00,20,00,22,00,25,00,31,00,22,\
  00,20,00,25,00,2a,00,00,00

[HKEY_CLASSES_ROOT\mscfile\shell\open\command]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
  00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,00,6d,00,\
  63,00,2e,00,65,00,78,00,65,00,20,00,22,00,25,00,31,00,22,00,20,00,25,00,2a,\
  00,00,00

[HKEY_CLASSES_ROOT\mscfile\shell\RunAs]
"HasLUAShield"=""

[HKEY_CLASSES_ROOT\mscfile\shell\RunAs\command]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
  00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,00,6d,00,\
  63,00,2e,00,65,00,78,00,65,00,20,00,22,00,25,00,31,00,22,00,20,00,25,00,2a,\
  00,00,00

[HKEY_CLASSES_ROOT\mscfile\shell\runasuser]
@="@shell32.dll,-50944"
"Extended"=""
"SuppressionPolicyEx"="{F211AA05-D4DF-4370-A2A0-9F19C09756A7}"

[HKEY_CLASSES_ROOT\mscfile\shell\runasuser\command]
"DelegateExecute"="{ea72d00e-4960-42fa-ba92-7792a7944c1d}"

[HKEY_CLASSES_ROOT\mscfile\shellex\ContextMenuHandlers\PintoStartScreen]
@="{470C0EBD-5D73-4d58-9CED-E91E22E23282}"

[HKEY_CLASSES_ROOT\mscfile\shellex\IconHandler]
@="{7A80E4A8-8005-11D2-BCF8-00C04F72C717}"

[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.msc]

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.msc\OpenWithProgids]
"MSCFile"=hex(0):

[-HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\DisallowRun]

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer]
"DisallowRun"=-

[-HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\DisallowRun]

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer]
"DisallowRun"=-

I hope that information helps. Let’s know your comments.