I first encountered this error when I was building a small media player using
WPF 4.0 and the embeddable open source database MySql. I added a link to the
MySql.Data.MySqlClient library which was built on a lower version of the .Net
framework than the one which the current application is running on. The screen
is as shown below
In order to correct the error, an app.config file must be added to the project
and then the following code is copied into the configuration file.