No, this is not a real Sinatra error :).
This is the personal homepage of Elad Meidar, a web developer and an entrepreneur specializing in Ruby on Rails. I hang around in Israel, and i am currently having the best time of my life over at Fiverr.com
I am a proud member of RailsBridge, Helping new Rails developers get into our world and also contributed a few Patches to the Ruby on Rails core.
Well, scaling an application in my opinion, i like doing the dishes after a really big dinner, nobody wants to do it, but you have to.
Just leaving it there will only make the process of cleaning and washing the dishes worst, and might add some more problems on the way.
Max Indelicato stats in his blog a list of 17 Distributed Systems and Web Scalability Resources which makes it easier to understand and to implement a proper application scaling policy, and on time.
You're seeing this error because I think it is funny.