When I was trying to run the asp .net application via Azure Emulator, Visual Studio showed me such an error “There was an error attaching the debugger to the IIS worker process bla-bla-bla”. There are a lot of causes for the situation. I would recommend the best way to troubleshoot this error is to try deploy the site to IIS manually and see if it runs. So I did that and it was not running. The 500 http error said me that an asp.net handler was incorrectly registered within IIS. So I went to “Turn Windows Features On\Off” and switched ASP .NET feature beside with authentication options. Restart and voila – everything worked!