asp.net4.0表单提交出现以下错误：
A potentially dangerous Request.Form value was detected from the client (txtBackInfo="<P>111111</P><P>&nbs...").
Description: Request Validation has detected a potentially dangerous client input value, and processing of the request has been aborted. This value may indicate an attempt to compromise the security of your application, such as a cross-site scripting attack. To allow pages to override application request validation settings, set the requestValidationMode attribute in the httpRuntime configuration section to requestValidationMode="2.0". Example: <httpRuntime requestValidationMode="2.0" />. After setting this value, you can then disable request validation by setting validateRequest="false" in the Page directive or in the <pages> configuration section. However, it is strongly recommended that your application explicitly check all inputs in this case. For more information, see http://go.microsoft.com/fwlink/?LinkId=153133.
解决方法如下：
1、修改web.config
<system.web>
<httpRuntime requestValidationMode="2.0" />
在<system.web>节点下加入<httpRuntime requestValidationMode="2.0" />
2、修改涉及aspx文件
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="BuMenTongZhiAdd.aspx.cs" Inherits="GongGao_BuMenTongZhiAdd" validateRequest="false" %>
加入validateRequest="false"
已验证问题解决