Visual Studio 2017 Doesn't Run Core Apps with

Question

I am having an issue with Visual Studio 2017 RC where when I run an MVC and/or WebAPI app using IIS Express the app never actually runs. Instead I get stuck with a page in the browser indicating it is trying to attach and from there it goes no further. If I open another tab/window in the browser and try to navigate directly to the launch URL, it just spins forever. Likewise when I run this using the dot net run command, the app launches and runs fine.

There do not seem to be any errors that I can see, just that the browser spins indefinitely without actually ever loading the page/endpoint.

Note: this occurs for most any circumstance. Newly created project in VS with no changes, known working project from previous versions, etc.

Answer 1

You could follow or upvote the issue: https://developercommunity.visualstudio.com/content/problem/11391/aspnet-core-iis-express-httplocalhost51733-failed.html

Looks like our workarounds meanwhile are

• dotnet run
• Publish to local IIS. Which is working for me.
• (Untested: downgrade from core-1.1 to core-1.0)

If you aren't familiar with VS2017/asp.net:

You have, or can reveal via View Menu-->Other Toolbars :

Debug toolbar --> dropdowncombobutton saying "[green arrow>] IIS Express"

• Click on the dropdown downarrow part of the button.

You should see a Run {yourprojectname} option. This is the equivalent of dotnet run {yourprojectname} from the commandline.

You can configure the options that appear in the dropdown with

Right-click on project in solution explorer --> Properties --> Debug

Answer 2

I had this same issue and after digging around for a while I discovered that I had dotnet preview v1.0.0-preview2 installed under Programs Files (x86) and a non-preview version in x64. I think VS is launching the x86 (preview) version but expecting to see the full version. To fix this, I did the following.

• from programs and feature uninstall every visible dotnet core. (note: for me this did not remove the x86 preview)
• go to https://www.microsoft.com/net/download/core#/sdk and install BOTH x86 and x64 SDK packages
• open command line and from the root directory check run: dotnet --version (at the time of writing it was 1.0.4)
• fire up .net core project in VS 2017 and run.

When I did all of the above, I was able to start up the site in IIS Express from VS.