We\'re using EngineYard Cloud to deploy our Ruby on Rails application. We are running Rails v2.3.3.
EngineYard Cloud deploys to AWS instances in a manner similar to
I've never gone to any length to figure out the details, but for me, this is a client-side data rot issue. If I've been messing around with the way I store my sessions (and therefore, my authorization details,) I get this error from time to time. Clearing out the private browser data; cookies, authenticated sessions, the works, has always solved it for me.
Hope this helps.