【转载】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 info

网上查到http://social.msdn.microsoft.com/Forums/vstudio/en-US/58271e39-beca-49ac-90f9-e116fa3dd3c0/mxed-mode-dll-unable-to-load-in-net-40?forum=clr

解决方案如下：

The only way the app config updates worked for me was to add it both to the dll assembly and the project using the dll. Also, I had to use the following config update. This is done on a VS2008 or VS2010 project ported to VS2012.
也就说在配置文件里加上如下信息即可：
<configuration>
  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0"/>
    <requiredRuntime version="v4.0.20506"/>
  </startup>
</configuration>

至此问题解决，大功告成！！！