Mixed mode assembly in .NET 4
I wrote a class library in .NET 2.0 for database access some 2 years ago and have been using it all along on .NET 2.0, 3.0 and 3.5. In the current project I'm working on (which is a .NET 4.0 application), tried using the old faithful class library and I got the following exception: System.InvalidOperationException was unhandled Message=An error occurred creating the form. See Exception.InnerException for details. The error is: Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information. Source