.net 4.0 A potentially dangerous Request.Form value was detected from the client 的解决方案

   <httpRuntime requestValidationMode="2.0" />这样  validate=false才会生效

<?xml version="1.0"?>
<!--
  有关如何配置 ASP.NET 应用程序的详细消息，请访问
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0"/>
<pages controlRenderingCompatibilityVersion="3.5" 
           validateRequest="false" clientIDMode="AutoID"/>
    <httpRuntime requestValidationMode="2.0" />
    <customErrors mode="Off"/>
  </system.web>
</configuration>