Here is an error I'll periodically get when starting and stopping multiple cloud projects over and over again. Every once in a while, after the project builds and while it is starting up the Compute Emulator, it'll throw one of these beauties:
I'm not sure quite what the problem is, but the solution is simple, albeit annoying.
To begin, it has helped me to change the properties on the cloud project to use IIS Server instead of IIS Express. To do so, right click on the cloud project and select "Properties." Select "Web" from the left hand menu. Select "Use IIS Web Server" from the radio button options.
Once the project is switched over to using IIS Server, there is really only one option left: close Visual Studio and exit out of Storage and Compute Emulator. The fastest way to achieve the latter step is to right click on the Compute Emulator icon in the task bar and select "Exit."
Now reopen your solution and it should fire up fine.