Unable to start program 'http://localhost/Default.aspx'. VS2010

Question

I cannot start my website from Visual Studio 2010 anymore.

For a few days I cannot start my project in a web browser using F5. When I open my web application directly by

Answer 1

I'll share my experience with this same problem. This is not a solution, but someone may be able to figure out the problem from my particular experience.

I've been having this same problem for a few weeks now. (I don't know what changed on my system.) I do not run as local admin, because we are not allowed to have admin privileges on our PCs where I work.

Until today, I could expect F5 (Start Debugging) to start up a new local VS web server, open an IE window, and then issue an "unable to start program http://localhost:nnnn/Login.aspx" and "access is denied" error pop-up. If I closed the IE window, waited a few seconds, and then clicked F5 again, it usually started up my web app in debug mode just fine from that point on.

But today, that all changed. I did not change any configuration on my web app, which has been running fine, but I did add a couple of more classes to one of my subprojects. At this point, I could never get past the "unable to start program" message. I could run my app without debugging, but that was rather pointless. I even tried attaching to a running (non-debug) IE process, but that did not work.

Finally, I modified some of the properties in the WebAppName >Web >Servers screen. Specifically, I enabled "Specific port" for a specific HTTP port (which VS had been using all along), and I disabled "NTLM Authentication". I also enabled "ASP.NET" in the Debuggers section. Some of these I first clicked, then unclicked, then clicked again, saving in between each click.

This time, running with debug (F5) worked.

After running several times, I still usually get a "unable to start" error the first time after a recompile, but I can still usually get a debuggable running app to start after the second or third try. At least I'm back to where I was yesterday.

I suspect it has do with VS reloading its execution profile, and also probably something to do with permissions (since I cannot run as admin).