Question: OK, this might sound a bit confusing and complicated, so bear with me.

We've written a framework that allows us to define friendly URLs. If you surf to any arbitrary URL, IIS tries to display a 404 error (or, in some cases, 403;14 or 405). However, IIS is set up so that anything directed to those specific errors is sent to an .aspx file. This allows us to implement an HttpHandler to handle the request and do stuff, which involves finding the an associated template and then executing whatever's associated with it.

Now, this all works in IIS 5 and 6 and, to an extent, on IIS7 - but for one catch, which happens when you post a form.

See, when you post a form to a non-existent URL, IIS says "ah, but that url doesn't exist" and throws a 405 "method not allowed" error. Since we're telling IIS to redirect those errors to our .aspx page and therefore handling it with our HttpHandler, this normally isn't a problem. But as of IIS7, all POST information has gone missing after being redirected to the 405. And so you can no longer do the most trivial of things involving forms.

To solve this we've tried using a HttpModule, which preserves POST data but appears to not have an initialized Session at the right time (when it's needed). We also tried using a HttpModule for all requests, not just the missing requests that hit 404/403;14/405, but that means stuff like images, css, js etc are being handled by .NET code, which is terribly inefficient.

Which brings me to the actual question: has anyone ever encountered this, and does anyone have any advice or know what to do to get things working again? So far someone has suggested using Microsoft's own [URL Rewriting module](http://learn.iis.net/page.aspx/460/using-url-rewrite-module/). Would this help solve our problem?

Thanks.

Answer: 
Microsoft released a hotfix for this : 

[<http://support.microsoft.com/default.aspx/kb/956578>](http://support.microsoft.com/default.aspx/kb/956578)
Just a guess: the handler specified in IIS7's %windir%\system32\inetsrv\config\applicationhost.config which is handling your request is not allowing the POST verb to get through at all, and it is evaluating that rule before determining whether the URL doesn't exist.