When trying to accept an HTML tag as input for one of the textbox in my ASP.NET MVC and saving the data , I received the below error .

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

How to Solve the error A potentially dangerous Request.Form value was detected from the client in ASP.NET MVC ?

One option is to set the validateRequest=”false” and/or add the following in the Web.config file under System.web tag.

<configuration>
    <system.web>
        <pages validateRequest="false" />
    </system.web>
</configuration>

<httpRuntime requestValidationMode="2.0"/>

If you want to display an proper error message when this error occurs , you can catch the exception in the Application error in the Global.asax file , identify if the error was HttpRequestValidationException and provide an custom error message in response.

void Application_Error(object sender, EventArgs e)
{
   Exception ex1 = Server.GetLastError();
   if (ex1 is HttpRequestValidationException)
   {
       Response.Clear();
       Response.StatusCode = 200;
       Response.Write(@"[html]");
       Response.End();
   }
}