I’ve run into this issue whenever setting up Microsoft DaRT 8.1 on Windows Server, and therefore assume that this is a common problem.

Microsoft DaRT 8.1 is intended to run on Windows Server 2012 R2 but installs fine on Windows Server 2012 RTM. This is as long as you run the setup file as an administrator install: 

msiexec /a MSDaRT81.msi 

Refer to Johan Arwidmark’s excellent blog post about setting up DaRT 8.1 together with MDT monitoring:

The issue I ran in to was when running DaRT Remote Control on the client from MDT Monitoring:

MMC has detected an error in a snap-in and will unload it.”

Microsoft DaRT - MMC has detected an error in a snap-in

After pressing “OK”, I saw these two error messages:

“Object reference not set to an instance of an object.”

mmc has detected an error in a snap-in in Deployment Workbench

This snap-in performed a non-valid operation and has been unloaded. To continue working with this snap-in, restart MMC or try loading the snap-in again.

Exception Type: System.NullReferenceException

Exception Message: Object reference not set to an instance of an object.

at. Microsoft.BDD.Workbench.MonitoringGeneral.buttonDaRT_Click(Object sender,EventArgs e)

Issue when running DaRT Remote Control MDT monitoring

How to troubleshoot the MMC snap-in error

To troubleshoot this behavior, I opened Process Monitor to see what happened when I pressed the “DaRT Remote Control” button. Download Process Monitor  from here:

I could see that DaRT (mmc.exe) was trying to access a registry key: “HKLM\SOFTWARE\Microsoft\DaRT”

Untitled picture3

Looking in the registry, I could see that there was no key with this name there.

How to fix the error

The solution was to create a string value called “InstallPath” which pointed to the installation path of DaRT.

The string value should be in HKLM:\SOFTWARE\Microsoft\DaRT\v8.1

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After making the registry change, I just started a new DaRT Remote Control session, and it worked perfectly 🙂


I have just described how to solve one MMC error related to Microsoft Dart. Fortunately, many new Microsoft products have moved away from MMC.

Please drop a comment if you know why this error occurs and if I am doing it wrong in any way 🙂

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