C# – ASP.NET 5 MVC: unable to connect to web server ‘IIS Express’


What I'm doing:

Deleting applicationhost.config, located in Documents\IISExpress\config, doesn't change the error message. (There's also an IISExpress folder in program files and program files (x86).)

Something I noticed, and I don't know if it's a problem:

Referenced file 'lib/jquery-validation/jquery.validate.js' not found.

I got a dump with rawcap but I don't notice much in there. Some of what was there:

"Framework":{"FrameworkName":"DNXCore,Version=v5.0","FriendlyName":"DNX Core 5.0","ShortName":"dnxcore50","RedistListPath":null}

I don't notice a problem, but I have the network data if that can help figure out why I cannot connect to the web server. I get a RST,ACK immediately so I'm guessing the port is closed and whatever this web server is, isn't being setup.

More on this problem: 800700c1 error from /trace:error

I've tried:

  • deleting applicationhost.config (and changing port number)
  • running visual studio as administrator
  • deleting IISExpress folder in Documents (changes error message until the folder is reinstalled)
  • toggling ssl off and on, copying url to launch box. (note: I'm not using ssl)
  • clearing all sfc /scannow errors
  • starting iisexpress with x86 version and 64-bit version

Best Solution

After installing Update 2 for Visual Studio 2015 I started getting the same error. I tried everything above with no luck. However, I found a solution that works for me:

  1. Delete YourSolutionFolder\\.vs\config\applicationhost.config file (note: .vs is a hidden folder)
  2. Open Visual Studio, right-click on web site > Properties > Debug tab > Web Server Settings > App URL - change port number.

If you have IIS configured to use the same port, (stop the application / use different port) and try again.