Dll project : 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.

Hi I have a dll project in C#.

I try to update his framework from 2 to 4.

Now when I use : SetDataSource, I have the error:

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.

I try to create an app.config file with:

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <startup useLegacyV2RuntimeActivationPolicy="true">

    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>

</startup>

  </configuration>

When I compile I have those file : myapp.dll and myapp.dll.config and planning.rpt

I use this dll in an other winform project (dll project is for plugin)

This winform project use also crstal report and I have an app.Config with the supportedRuntime line and there is no problem.

Have you a solution?

Thank you.

Gwenael