How can I reference a dll in the GAC from Visual Studio?

Question

As the others said, most of the time you won't want to do that because it doesn't copy the assembly to your project and it won't deploy with your project. However, if you're like me, and trying to add a reference that all target machines have in their GAC but it's not a .NET Framework assembly:

1. Open the windows Run dialog (Windows Key + r)
2. Type C:\Windows\assembly\gac_msil. This is some sort of weird hack that lets you browse your GAC. You can only get to it through the run dialog. Hopefully my spreading this info doesn't eventually cause Microsoft to patch it and block it. (Too paranoid? :P)
3. Find your assembly and copy its path from the address bar.
4. Open the Add Reference dialog in Visual Studio and choose the Browse tab.
5. Paste in the path to your GAC assembly.

I don't know if there's an easier way, but I haven't found it. I also frequently use step 1-3 to place .pdb files with their GAC assemblies to make sure they're not lost when I later need to use Remote Debugger.

Registering assmblies into the GAC does not then place a reference to the assembly in the add references dialog. You still need to reference the assembly by path for your project, the main difference being you do not need to use the copy local option, your app will find it at runtime.

In this particular case, you just need to reference your assembly by path (browse) or if you really want to have it in the add reference dialog there is a registry setting where you can add additional paths.

Note, if you ship your app to someone who does not have this assembly installed you will need to ship it, and in this case you really need to use the SharedManagementObjects.msi redistributable.

I've created a tool which is completely free, that will help you to achieve your goal. Muse VSReferences will allow you to add a Global Assembly Cache reference to the project from Add GAC Reference menu item.

Hope this helps Muse VSExtensions

In VS2010, from the Add Rerences window you can click 'Browse' and navigate to C:\Windows\Assembly and add references to the assemblies that you want. Please note that the files may be grouped under different folders like GAC, GAC_32, GAC_64, GAC_MSIL etc.

In VS, right click your project, select "Add Reference...", and you will see all the namespaces that exist in your GAC. Choose Microsoft.SqlServer.Management.RegisteredServers and click OK, and you should be good to go

EDIT:

That is the way you want to do this most of the time. However, after a bit of poking around I found this issue on MS Connect. MS says it is a known deployment issue, and they don't have a work around. The guy says if he copies the dll from the GAC folder and drops it in his bin, it works.

The only way that worked for me, is by copying the dll into your desktop or something, add reference to it, then delete the dll from your desktop. Visual Studio will refresh itself, and will finally reference the dll from the GAC on itself.