# Superclass mismatch with Rails 3 **URL:** \ **Category:** Rails\ **Created:** [April 1, 2010, 5:17pm UTC](https://www.ruby-forum.com/t/superclass-mismatch-with-rails-3/186176 "2010-04-01T17:17:02Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![philostler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/dbc845/32.png) [@philostler](https://www.ruby-forum.com/u/philostler)\ **Post date:** [April 1, 2010, 5:17pm UTC](https://www.ruby-forum.com/t/superclass-mismatch-with-rails-3/186176/1 "2010-04-01T17:17:02Z")
I’m currently developing a Rails 2 project that I’d like to migrate across to Rail 3. However I’m having real trouble in the first place getting Rails 3 to work straight out of the box with a blank project. Initially I tried getting this working a JRuby 1.5 snapshot & then 1.4. I’ve now been trying the same with Ruby 1.9.1-p378-rc2 from RubyInstaller with the same results. The error: Upon executing “ruby script\rails server” (rails server doesn’t work in Windows. Running Win7 btw) I always get the following error… C:\Users\Phil O.\Desktop\Project\Rails\>ruby script\rails server C:/Users/Phil O./Desktop/Project/Rails/config/application.rb:9:in `': superclass mismatch for class Application (TypeError) from C:/Users/Phil Ostler/Desktop/Project/Rails/config/application.rb:8:in`\’ from C:/Ruby19/lib/ruby/gems/1.9.1/gems/railties-3.0.0.beta/lib/rails/co mmands.rb:36:in `require' from C:/Ruby19/lib/ruby/gems/1.9.1/gems/railties-3.0.0.beta/lib/rails/co mmands.rb:36:in`\’ from script/rails:10:in `require' from script/rails:10:in`’ I’ve tried using the latest gems as well as following any guides I could find and matching the gem versions they used but always get the same result. Current local gem list: \*\*\* LOCAL GEMS \*\*\* abstract (1.0.0) actionmailer (3.0.0.beta) actionpack (3.0.0.beta) activemodel (3.0.0.beta) activerecord (3.0.0.beta) activeresource (3.0.0.beta) activesupport (3.0.0.beta, 2.3.5) arel (0.2.1) builder (2.1.2) bundler (0.9.10) erubis (2.6.5) i18n (0.3.5) mail (2.1.3) memcache-client (1.7.8) mime-types (1.16) polyglot (0.3.1) rack (1.1.0) rack-mount (0.6.0, 0.4.7) rack-test (0.5.3) rails (3.0.0.beta) railties (3.0.0.beta) rake (0.8.7) rubygems-update (1.3.6) text-format (1.0.0) text-hyphen (1.0.0) thor (0.13.4) treetop (1.4.5) tzinfo (0.3.16) I’ve googled this and vaguely understand the error but don’t know how to go about fixing it. I get the feeling this might not be my setup and more a gem that’s breaking Rail 3 but that could be miles off the mark. Any suggestions? Cheers, Phil ---
**Author:** ![philostler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/dbc845/32.png) [@philostler](https://www.ruby-forum.com/u/philostler)\ **Post date:** [April 1, 2010, 8:16pm UTC](https://www.ruby-forum.com/t/superclass-mismatch-with-rails-3/186176/2 "2010-04-01T20:16:47Z")
“Phil O.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote in message news:removed\_email\_address@domain.invalid… > I’m currently developing a Rails 2 project that I’d like to migrate > across to Rail 3. However I’m having real trouble in the first place > getting Rails 3 to work straight out of the box with a blank project. First a hint. There is a gem named rails3b that somebody in the rails core team created to pull in the missing dependecies of the Rails gem when using the rails 3 beta. Second, Your problem is naming the test application “Rails”. That results in a module named “Rails” that contains your application, but the Rails module is part of Rails’ own namespace. Thus your config/application.rb is trying to create or re-open a Rails::Application class that is derived from Rails::Application. I’m not an expert in that corner of Ruby, but I’m not sure tryingg to have a class derive from itself could ever be expected to work. Further Rails::Application is already defined, and it has a different base class, so ruby has no idea what to do, so it spits out an error and stops. Try creating a project with a unique name. You should probably find that works better. ---
**Author:** ![philostler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/dbc845/32.png) [@philostler](https://www.ruby-forum.com/u/philostler)\ **Post date:** [April 2, 2010, 2:02pm UTC](https://www.ruby-forum.com/t/superclass-mismatch-with-rails-3/186176/3 "2010-04-02T14:02:11Z")
Indeed you are right, changing the name of my application has fixed this. Thank you! Reason for me naming it Rails is because I have separate folders in my project development for different elements (e.g. Rails, Database Schema, Flex) and it always worked in Rails 2 fine for me this way. I’ve used rails3b before but was mix and matching gem versions to try and get around this problem. Now running Ruby 1.9.1-p378-rc2 with Rails 3.0.0.beta2! Next stop, JRuby 1.5.0 dev snapshot… Cheers! ---
**Author:** ![philostler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/dbc845/32.png) [@philostler](https://www.ruby-forum.com/u/philostler)\ **Post date:** [April 2, 2010, 3:26pm UTC](https://www.ruby-forum.com/t/superclass-mismatch-with-rails-3/186176/4 "2010-04-02T15:26:14Z")
On Fri, Apr 2, 2010 at 8:02 AM, Phil O. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Now running Ruby 1.9.1-p378-rc2 with Rails 3.0.0.beta2! > From what I’ve read 1.9.1 is NOT recommended for use with Rails3 beta > 2, they want us to use the latest pre-release version of 1.9.2 > instead. > – > Rick DeNatale Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/) Github: [rubyredrick (Rick DeNatale) · GitHub](http://github.com/rubyredrick) Twitter: @RickDeNatale WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale) LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale)