is this something basic or am I missing something?
My ASP.NET (4.0) site has a web.config with URL rewrite rules. When I run it in debug mode (local webserver) all the URLs fail because the local web server does not recognize the rules (e.g. I have /register which maps to register.aspx etc.)
Is there someway I can get the debug system to recognize my URL rewrite rules? Should I be doing something else?
Make sure that you have the URL Rewriting Module installed in your IIS. (I assume you mean IIS with local webserver. Cassini won't work)
Its definetly possible to debug a webapplication running on local IIS that uses URL Rewriting
The best bet seems to be to move to IIS Express if you can, since that can use the same URL Rewriting module as "real" IIS, and should also have fewer other bug-causing differences than Cassini has.
An alternative would be to do your rewriting with UrlRewritingNet if that'll handle the rules that you need. That's a .NET HttpModule, so it'll work on either Cassini or IIS.