# What does undefined method \`session=' for ActionController::Base:Class mean?

**URL:** <https://www.ruby-forum.com/t/what-does-undefined-method-session-for-actioncontroller-class-mean/130132>\
**Category:** Deployment\
**Created:** [February 25, 2008, 5:30pm UTC](https://www.ruby-forum.com/t/what-does-undefined-method-session-for-actioncontroller-class-mean/130132 "2008-02-25T17:30:50Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [February 25, 2008, 5:30pm UTC](https://www.ruby-forum.com/t/what-does-undefined-method-session-for-actioncontroller-class-mean/130132/1 "2008-02-25T17:30:50Z")

</div>

Hi,

I’m trying to take a rails project built on gem version 1.2.6 and  
upgrade it to 2.0.2. So far, I haven’t changed anything except this  
line in the config/environment.rb file …

RAILS\_GEM\_VERSION = ‘2.0.2’ unless defined? RAILS\_GEM\_VERSION

when I start the server, I get this error:

[me@mymachine]~/w/dps% ruby script/server  
=\> Booting WEBrick…  
./script/…/config/…/vendor/rails/railties/lib/initializer.rb:334:in  
`send': undefined method`session=’ for ActionController::Base:Class  
(NoMethodError)  
from ./script/…/config/…/vendor/rails/railties/lib/  
initializer.rb:334:in `initialize_framework_settings' from ./script/../config/../vendor/rails/railties/lib/ initializer.rb:333:in`each’  
from ./script/…/config/…/vendor/rails/railties/lib/  
initializer.rb:333:in `initialize_framework_settings' from ./script/../config/../vendor/rails/railties/lib/ initializer.rb:330:in`each’  
from ./script/…/config/…/vendor/rails/railties/lib/  
initializer.rb:330:in `initialize_framework_settings' from ./script/../config/../vendor/rails/railties/lib/ initializer.rb:100:in`process’  
from ./script/…/config/…/vendor/rails/railties/lib/  
initializer.rb:47:in `send' from ./script/../config/../vendor/rails/railties/lib/ initializer.rb:47:in`run’  
… 11 levels…  
from /usr/local/apache2/htdocs/dps/vendor/rails/activesupport/  
lib/active\_support/dependencies.rb:495:in `require' from /usr/local/apache2/htdocs/dps/vendor/rails/railties/lib/ commands/server.rb:39 from script/server:3:in`require’  
from script/server:3

What does it mean and any ideas how to fix/troubleshoot? Thanks, -  
Dave