Compiler Error Message: CS0012: The type 'System.Data.Objects.DataClasses.EntityObject' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

头次碰到这个问题，google结果，需要修改web.config文件

添加配置节点

<configuration>

  <system.web>

    <compilation>

      <assemblies>

        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral,PublicKeyToken=b77a5c561934e089"/>

      </assemblies>

    </compilation>

  </system.web>

</configuration>

http://*.com/questions/1501616/is-the-combination-of-ado-net-entity-framework-and-asp-mvc-wrong-by-any-chance

http://*.com/questions/3219412/strange-compilation-error-in-entity-framework-and-mvc-application