How do I fix a corrupted copy of .Net Framework on Windows 7?

Question

I receive the following error when trying to run applications that require .net Framework 3.5:

Could not load file or assembly 'System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The module was expected to contain an assembly manifest.

I've tried numerous fixes, such as reinstalling through ad/remove software, copying the .net folder over from a clean windows 7 install, and running the .net cleanup tool.

Just wondering if anyone has run into this issue before, or has an idea on how to fix it.

Solution

Are you encountering errors uninstalling the framework?

You could try this clean uninstall, from a guy who works at MS, then reinstall here @ http://www.microsoft.com/net/download.aspx although you've said you've ran a cleanup tool already.

http://blogs.msdn.com/b/astebner/archive/2008/08/28/8904493.aspx

Comments

[Synetech]

The problem is that .NET 3.5.1 comes with Windows 7 and cannot be uninstalled through Optional Features, well not actually (though you can force it manually but that creates problems if you don't reinstall it). Simply copying over the .NET folder isn't enough because there are registry entries that are needed. The .NET cleanup tool is the .NET equivalent of the MSI Zap tool and forcibly wipes .NET, allowing you to reinstall. What happened when you ran it? Do you get an error?

[Iverelo]

When I use the ad/remove windows features to uncheck .net framework 3.5.1, it shows a progress bar for a short time. Then, when I re-check it, it goes through the same progress bar again. I don't think either activity is actually doing anything.

[Luke Hutton]

Can you try these steps here? blogs.msdn.com/b/astebner/archive/2007/03/26/… Seems to apply to Win7 too