Old web application on server with .NET 4.0 stopped working
<p>I have an old ASP.NET web application on a server, which was developed in Visual Studio 2008 in the year 2008. The server now has .NET 4.0 installed also. When I try to access the web app I get:</p>

<pre><code>Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS1703: An assembly with the same identity 'System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' has already been imported. Try removing one of the duplicate references.

Source Error:

[No relevant source lines]
</code></pre>

<p>Is there anything I can do to get it to work without access to the original Visual Studio solution? I believe it has to do with the fact that .NET 4.0 is also installed on the server.</p>
