Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additio

最近在用VS2010 进行.net 4.0开发时报了如上这条错误

 

项目为 WINFORM,引用的DLL为2.0 而主项目为4.0 于是这个错误：

 

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.

 

将DLL转为 4.0 依旧报这个错误

 

最后在CONFIG 中添加如下代码解决：

 

 

<CONFIGURATION>
<STARTUP useLegacyV2RuntimeActivationPolicy="true">
<SUPPORTEDRUNTIME version="v4.0" />
<REQUIREDRUNTIME version="v4.0.20506" />
</STARTUP>
</CONFIGURATION>

 

 

原文地址：http://social.msdn.microsoft.com/Forums/en/clr/thread/58271e39-beca-49ac-90f9-e116fa3dd3c0

 

注意：VS2010 默认也会根据项目添加 STARTUP这个节点，但是仍然会报错。

 

需要手动添加如下代码，问题才得以解决：

useLegacyV2RuntimeActivationPolicy="true"

<REQUIREDRUNTIME version="v4.0.20506" />