此方法显式使用的 CAS 策略已被 .NET Framework 弃用。若要出于兼容性原因而启用 CAS 策略，请使用 NetFx40_LegacySecurityPolicy 配置开关

Just add this

<NetFx40_LegacySecurityPolicy enabled="true"/>

into your VS2010 DevEnv configuration file, you'll find it in C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe.config

There is a <runtime> section, just copy it at the first place.
I've had the same problem with DevExpress 8.2

If some people face the same problem while developing ASP.Net apps, they should add the Attribute to the Cassini config file placed in C:\Program Files (x86)\Common Files\microsoft shared\DevServer\10.0\WebDev.WebServer40.exe.config

<runtime> <NetFx40_LegacySecurityPolicy enabled="true"/> </runtime> 在

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe.config

设置

修改前请备份

参考：

http://stackoverflow.com/questions/2637089/netfx40-legacysecuritypolicy-in-design-time-mode

<runtime> <NetFx40_LegacySecurityPolicy enabled="true"/> </runtime> 在

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe.config

设置

修改前请备份

参考：

http://stackoverflow.com/questions/2637089/netfx40-legacysecuritypolicy-in-design-time-mode