# Undefined method \`subclasses' error

**URL:** <https://www.ruby-forum.com/t/undefined-method-subclasses-error/89836>\
**Category:** Rails\
**Created:** [March 23, 2007, 1:14am UTC](https://www.ruby-forum.com/t/undefined-method-subclasses-error/89836 "2007-03-23T01:14:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![bithai80](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/d26b3c/32.png) [@bithai80](https://www.ruby-forum.com/u/bithai80)\
**Post date:** [March 23, 2007, 1:14am UTC](https://www.ruby-forum.com/t/undefined-method-subclasses-error/89836/1 "2007-03-23T01:14:59Z")

</div>

hi, I moved up from rails 1.1.6 to 1.2.3 and now i get this error:

Processing ApplicationController#login (for 74.193.67.252 at 2007-03-22  
18:04:47) [GET]  
Session ID: 3cf7c4e3edc74e0912bf74c9e309750a  
Parameters: {“action”=\>“login”, “controller”=\>“account”}

NoMethodError (undefined method `subclasses' for #<Set: {User, Coach}>): /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/core_ext/symbol.rb:10:in` **send** ’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active\_support/core\_ext/symbol.rb:10:in  
`to_proc' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/inflector.rb:250:in`map’  
/usr/lib/ruby/1.8/set.rb:189:in `each' /usr/lib/ruby/1.8/set.rb:189:in`each\_key’  
/usr/lib/ruby/1.8/set.rb:189:in `each' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/core_ext/enumerable.rb:42:in`map’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active\_support/core\_ext/enumerable.rb:42:in  
`sum' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/observer.rb:170:in`observed\_subclasses’  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/observer.rb:149:in  
`initialize' /usr/lib/ruby/1.8/singleton.rb:95:in`new’  
/usr/lib/ruby/1.8/singleton.rb:95:in `instance’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action\_controller/deprecated\_dependen

Any ideas? Thanks.

---

<div class="post-metadata">

**Author:** ![bithai80](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/d26b3c/32.png) [@bithai80](https://www.ruby-forum.com/u/bithai80)\
**Post date:** [May 3, 2007, 2:39pm UTC](https://www.ruby-forum.com/t/undefined-method-subclasses-error/89836/2 "2007-05-03T14:39:46Z")

</div>

I also moved up from 1.2.2 to 1.2.3, however when I start the server (or  
even script/about) I have this error:

/opt/local/lib/ruby/gems/1.8/gems/activesupport-1.4.2.6552/lib/active\_support/core\_ext/module/aliasing.rb:31:in  
`alias_method’: undefined method`load\_plugin’ for class  
`Rails::Initializer’ (NameError)

Rails 1.2.2 with ActiveSupport 1.4.1 works fine, but when I want to have  
ActiveResource, I need at least 1.2.3 and 1.4.2 that don’t start in  
proper way.