My mobile site does not render on certain mobile phones. Why?

Question

I am developing a basic mobile site in asp.NET and C# and am having problems rendering .aspx pages on certain mobile phone browsers.

I tried Stackoverflow.Mobi on a nokia looking for good examples for coding mobile sites. As soon as I redirect to another page I receive the error "File Format Unknown."

As soon as i use the button_click event to transfer to another page the "File Format Unknown." shows up on the mobile divice.

I have tried the following as suggested fixes from numerous forums but without any luck.

1. Setting Page contentype : ContentType="text/html"
2. Server.Transfer
3. Response.ContentType = "application/xhtml+xml";
   Response.Redirect("Test.aspx");
4. Posting to the Full URL www.XXXX.com/test.aspx

One of the phones i am having problems with is a Nokia 6300

Any suggestions?

Answer 1

Normaly this is a problem with doc-type, because asp.net changes it to wap/application. I will recommend you use Fiddler for checking http headers. Normaly,Page directive ContentType should solve it

<%@ Page Language="C#" ... ContentType="text/html" %>

But you have set :-S

Answer 2

Make sure your html passes w3c validation. I know Blackberry device will have trouble displaying pages where the Html does not validate according to the doctype.