Chk my SO Post
Finally, I'm able to crack it for VS.Net 2015 and its configuration of IISExpress. ITs not possible to configure it 'externally' and nothing will work if you keep modifying IIS or IISExpress settings outside VS.Net.
It took me a while to narrow down my focus to VS.Net proj properties and configurations. I found that VS.Net created its own version of "applicationhost.config" which can be found at -
<myProject.sln path> \.vs\config\applicationhost.config
This is the file in which I had to change the application pool (applicationPool="Clr4ClassicAppPool) -
<sites>
<site name="WebSite1" ... ignore this sction if present
</site>
<site name="myProject" id="2">
<application path="/" applicationPool="Clr4ClassicAppPool">
<virtualDirectory path="/" physicalPath="D:\Source\myProject" />
</application>
<bindings>
<binding protocol="http" bindingInformation="*:1960:localhost" />
</bindings>
</site>
You just need to change the applicationPool (your Classic App pool name might be diff in that case get the correct one from in the same file). Also make sure you're updating the correct "site" node (the correct localhost url of your web app when debugged from VS.Net)
If still there's an issue set the following -
<applicationDefaults applicationPool="Clr4IntegratedAppPool" />
Hope this helps.