I got the exception shown below when I opened an application that was developed under VS 2008:
ASP.NET runtime error: Could not load file or assembly ‘System.Data.DataSetExtensions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089′ or one of its dependencies. The system cannot find the file specified
What’s happened is there is no more an assembly System.Data.DataSetExtensions with version number 2.0. There is a new version for the same assembly name under 3.5.0.0.
To resolve the problem, simply right-click on the web application, properties, then remove the reference to the 2.0.0.0 assembly.
Then, right-click on the web application solution, Add Reference, locate the System.Data.DataSetExtensions and add a reference to it. You may also need to update the entry web / app.config file under the <assemblies> tag. Update the version to 3.5.0.0



