What is debugattach.aspx and why can't the server find it?

Question

I\'m developing on an XP (SP3) machine with VS 2010 and IIS 5.

I have two versions of the same site. We\'ve released our first production version, so I forked the c

Answer 1

Based on this old posting, DebugAttach.aspx is implemented by the HTTP handler System.Web.HttpDebugHandler. I did not actually see this handler referenced anywhere in IIS7 though - it's possible that this implementation was merged into some other handler down the road. Definitely some sort of handler though. When it's working, you see 200 (success) messages in the logs.

I had this same problem 2 different ways, where F5 debugging failed in VS2010 because of a problem reaching the debug handler. Using the IIS Failed Request Tracing logs, I was able to see instances where IIS modules were interfering. In once case, UrlScan.dll was blocking the DEBUG verb. In another, a redirect from HTTP to HTTPS was causing the debug handler to return a 302. In both cases, VS barfed with a similar dialog.

At any rate, the trick here seems to be figuring out how a DEBUG request to this URL can be blocked.