Email address in a textbox causes PageRequestManagerServerErrorException - asp.net

Question

I have a multiline textbox within an updatePanel. where a user can enter any notes he requires. If he enters an email address inside angular brackets then when submitting or cancelling I get a PageRequestManagerServerErrorException of 500.
If he enters an email address in these notes as myaddress.xxx.ca without the brackets, then there is no error.
The textbox should allow him to enter anything he wants too, it is really just for his notes.
I have tried to the RequestValidation = "false" in the page directive but this does not work.
Any suggestions would be appreciated.
Bryan

Answer 1

I assume you are using at least .Net 4.0? I did a small example according to your question and noted the same behaviour. Fortunatelly I found a quick solution (even here on Stackoverflow - Allow html in asp.net textboxes).
aspx
<%# Page Language="C#" AutoEventWireup="true" ValidateRequest="false" CodeFile="commonQuestions.aspx.cs" Inherits="commonQuestions" %>
.....
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:TextBox ID="TextBox1" runat="server" Height="81px" TextMode="MultiLine" Width="264px"></asp:TextBox>
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Send" />
</ContentTemplate>
</asp:UpdatePanel>
</form>
codeBehind
protected void Button1_Click(object sender, EventArgs e)
{
// do something
Debug.WriteLine("Text: " + TextBox1.Text);
}
add to web.config
<httpRuntime requestValidationMode="2.0" />
And here we got a pretty good explanation from MS, refering to changes in ASP.Net 4
As a result, request validation errors might now occur for requests
that previously did not trigger errors. To revert to the behavior of
the ASP.NET 2.0 request validation feature, add the setting (see above)
in the Web.config file: