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Visual Studio 2010 cannot reference ManagedDTS dll from SQL Server 2005

A C# project that worked with Visual Studio 2008, when converted to Visual Studio 2010, starts complaining about not being able to find classes defined in Microsoft.SQLServer.ManagedDTS.dll and others. These dlls are contained in the SQL Server 2005. If you try to remove the reference and add it again, the errors disappear in the editor, but appear again when you compile the solution. At the end of the jumble of compiler errors there is a small one that betrays the cause:

warning MSB3258: The primary reference "Microsoft.SQLServer.ManagedDTS, Version=, Culture=neutral, PublicKeyToken=89845dcd8080cc91, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the .NET Framework assembly "mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" which has a higher version "2.0.3600.0" than the version "" in the current target framework.

The problem lies in the Microsoft.SQLServer.msxml6_interop.dll that references the beta version of the .Net framework 2.0. Yes, even after installing three service packs – and worse still, even if you install SQL Server 2008 it will remain there. Why? Apparently, there’s a newer msxml6_interop dll with this reference fixed but unfortunately it has the same version as the old one so it doesn’t replace it in the GAC. Talk about eliminating DLL hell.

But that’s not all, you cannot simply find the new dll and replace it in the GAC. The old one cannot be removed because it’s referenced by the Windows Installer. You have to use brute force, something like this: open the command prompt and try to find the real path to the assembly on the disk. (From Windows Explorer you cannot do this because it replaces the real GAC folder structure with a conceptual, flat view). So, CD to c:\Windows\Assembly and find the folder called Microsoft.SqlServer.msxml6_interop. In it, there will be another folder called something like, and in it the dll we’ve been looking for. On my computer, the full path is


Ok, now you should be able to manipulate the dll directly and replace it with the new one. What I like to do in these cases is SUBST the folder and make it accessible from Windows Explorer. Type something like this -

SUBST x: c:\windows\assembly\GAC_MSIL\Microsoft.SqlServer.msxml6_interop\

- and you will be able to see the folder in Windows Explorer as a separate volume X:. From here you can delete the existing file and copy over the newer one. You can find the new one only if you have a machine where SQL Server 2008 is installed first – it’s in the same (or similar) place in the GAC. I used again the command prompt trick to get the file. (Note that I did everything as administrator, you might have to employ additional tricks to work around security).

Here’s a more detailed description with other possible solutions:


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