html.actionlink with .net 4.0 renders empty links

Question

This should hopefully be a simple configuration problem.

When my application targets .Net 3.5

This code

<%= Html.ActionLink("Forgot your password?","ForgotPassword") %>

renders this:

<a href="/Account/ForgotPassword">Forgot your password?</a> 

When my application targets .Net 4.0

The same code renders:

<a href="">Forgot your password?</a> 

It's dropping the url part.

backwards compatibility is supposedly enabled in my web.config.

<pages controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID">

Ideas?

Answer 1

This had to do with the default map route having an extra value. It looks like .Net 4.0 is less forgiving about bad path mapping.

Answer 2

http://haacked.com/archive/2010/02/12/asp-net-mvc-2-optional-url-parameters.aspx