Today I received the following error when trying to start debugging on a web site in Visual Studio 2013:
————————— Microsoft Visual Studio —————————
Unable to start debugging on the web server. The underlying connection was closed: An unexpected error occurred on a send. Click Help for more information.
————————— OK Help —————————
The problem was that the site had a binding configured to use https but no certificate had been selected. After selecting a certificate the site opened correctly.