It's beyond me as to why IIS Express is even being used. I have never seen it used on any client's development machine. I don't even use IIS Express in my home development environment, which is no better than the VS Web developer trash that use to
be part of VS that IIS Express replaced.
I always have Web development projects through VS deployed to local IIS so that the solution can be run and debugged through Visual Studio against local IIS and eliminate IIS Express out of the picture.
https://msdn.microsoft.com/en-us/library/ms178108.aspx
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To specify the Web server for a Web application project
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One must start VS using Run As Administrator.
You can also try the IIS forum about IIS Express.
https://forums.iis.net/