"An operation is not legal in the current state" error when trying to launch ASP.NET project in VS2013?

Question

I have an ASP.NET web site created with WebMatrix 3. I do have the option in VS2013 checked to use the 64-bit version of IIS Express since I am running on 64-bit Windows 8.1. When I try to launch the project I get the error "An operation is not legal in the current state". Does anybody know how to fix this?

Answer 1

I got this same error "An operation is not legal in the current state" when running a project on Google Chrome, Stopping the project then closing all chrome instances fixed the problem.

I think it's related to visual studio not being able to attach to chrome instance for debugging.

Answer 2

Closing Chrome and restarting IIS (e.g. in IIS Manager) should solve the issue. It helped in my case.