Unable to deploy solution on Windows Server 2012 (4272421)

Content Matrix installation fails with the following error message:

Cannot add the specified assembly to the global assembly cache: Metalogix.SmartThreadPool.dll

You may also see the following in the ULS Log:

Access denied. Only machine administrators are allowed to create administration service job definitions of type: Microsoft.SharePoint.Administration.SPSolutionDeploymentJobDefinition, Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c.

UAC (User Account Control) does not allow deployment to the Global Assembly Cache (GAC).

When deploying Metalogix WSPs on Windows Server 2012, follow the steps below:

1. Disable "User Account Control: Run all administrators in Admin Approval Mode".
   
   
    
2. Restart the machine.
3. Uninstall Metalogix DLLs from the C:\Windows\assembly folder.
   
   
    
4. Remove 6.x.x.x folders from ..\15\ISAPI\ML.
   
   
    
5. Perform an IISRESET, and then install the latest Content Matrix version.

Note: On some Windows 2012 servers, GAC can show sub-folders under C:\Windows\Assembly. Some DLLs get installed under sub-folders. To fix this, re-register the DLL that controls the GAC Cache Viewer by running the command below:

regsvr32 "C:\Windows\Microsoft.NET\Framework\v2.0.50727\shfusion.dll"