From: Markus Date: 2007-07-27T01:19:30+09:00 Subject: [Rails] NameError: ApplicationAPI Just for the record... I've seen occasional mentions of a problem people have had upgrading existing Rails 1.1.x applications to Rails 1.2.x, leading to complete failure of the application with the message: NameError: Neither ApplicationApi or ApplicationAPI found ...but I've never seen a general solution posted, or even an explanation of what caused it. (Google finds this: http://weblog.oriontransfer.co.nz/articles/2007/04/12/rails-1-2-2-problem-with-older-engines but it appears not to have helped most people). Yesterday I ran into the problem myself and thought I should post the probable cause and likely fix for posterity. The problem: The older application has web services enabled but is not actually using / defining and web services (i.e., does not define the class ApplicationAPI). This was not a problem in earlier versions of Rails as the didn't try to access the API if it wasn't defined; later versions apparently assume that if you are using web services you have an API defined. What is likely to fix it: find the line(s) in config/environments.rb that disable unused frameworks and make sure that you are disabling web_services: config.frameworks -= [:action_web_service, ... ] You may also need to check config/environments/*.rb as the settings there would override those in environments.rb. --MarkusQ