Whilst trying to get an old Rails app up and running with Thin (Gem version 1.2.2) then I encountered a spot of bother:
load_missing_constant: uninitialized constant ActionController::Dispatcher (NameError)
I can’t remember the exact point of change, but remember that Dispatcher changed into ActionController::Dispatcher somewhere along the line - obviously after Rails 1.2.3 and 1.2.6!
There was already a check in place within Thin to see if the call method could be used on the Dispatcher - the trouble being that because ActionController::Dispatcher isn’t defined then it fails!
I’ve submitted a ticket - a simple check to make sure ActionController::Dispatcher is defined - in the meantime then I’ve also put a patch up as a gist to get things running.