Heres a good one. Today I was working away and fixed a simple bug. Then hit F5 again and VS says” Can’t start app in debug mode.
er. Restart VS and try again. Same deal.
So, hit Control + F5. Get a 503 error this time.
With a quick search I found this: http://www.dotnetfunda.com/articles/article1471-service-unavailable-http-error-503-the-service-is-unavailable-sharepoint-.aspx
So, I opened IIS Admin and sure enough, then Default AppPool was stopped. Restarted it and now it works.
Weird.