Unable to connect IIS Express - Visual Studio 2017

 Delete your web application’s .vs\applicationhost.config and try rebuilding the application and launching.

.vs is a hidden folder under your solution's folder.

The specified framework 'Microsoft.NETCore.App', version '1.0.0' was not found

Error white running EF framework command

Resolution
Install latest .NET Core SDK

https://github.com/dotnet/core/blob/master/release-notes/download-archives/1.1.2-download.md