A potentially dangerous Request.Form value was detected from the client

Server Error in '/' Application.

 

A potentially dangerous Request.Form value was detected from the client (txtCode="<br/>").

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.

Exception Details:System.Web.HttpRequestValidationException: A potentially dangerous Request.Form
value was detected from the client (txtCode="<br/>").
 
You have to do little modification to you application to get this fixed.

  1. Add <httpRuntime requestValidationMode="2.0" /> in your application web.config
       under <system.web>.
       <system.web>
        <httpRuntime  requestValidationMode="2.0"/>
  2. Add RequestValidation="false" on your page or in web.config <pages>
       attribute.
    <%@ Page Language="C#" AutoEventWireup="true" ValidateRequest = "false"
     
    or
    to work this for whole application do in web.config as:
    <system.web>
        <httpRuntime  requestValidationMode="2.0"/>
        <pages validateRequest ="false"></pages>