Redmine

Hi all,
I have upgraded my old 1.4 redmine to 2.3.1 first on a local machine, then on a production server. In both cases I use the development version.

Nevertheless, on the prod server the models return many "NameError (undefined local variable or method ..." resulting in a 500 error.

This is visible in rails console too. For example:

LOCAL SERVER
irb(main):001:0> Tracker
=> Tracker(id: integer, name: string, is_in_chlog: boolean, position: integer, is_in_roadmap: boolean, fields_bits: integer)

PROD SERVER
irb(main):001:0> Tracker
=> Tracker(id: integer, name: string, is_in_chlog: boolean, position: integer, is_in_roadmap: boolean)

Of course when I try to browse issues, the prod server log reports:
NameError (undefined local variable or method `fields_bits' for #<Tracker:0xc1dd240>):
app/models/tracker.rb:72:in `block in disabled_core_fields'
app/models/tracker.rb:72:in `select'
app/models/tracker.rb:72:in `disabled_core_fields'
app/models/tracker.rb:96:in `map'
app/models/tracker.rb:96:in `disabled_core_fields'
app/models/issue_query.rb:182:in `initialize_available_filters'
app/models/query.rb:309:in `available_filters'
app/models/query.rb:200:in `build_from_params'
app/helpers/queries_helper.rb:197:in `retrieve_query'
app/controllers/issues_controller.rb:56:in `index'

Whiny nils are disabled.
Codebase and configuration is pretty the same. The only difference is that local server is x86_64, the prod server is an i686 virtual machine. Both are Ubuntu 12.04 with ruby-1.9.3-p392 installed via rvm.

RAILS_ENV=development script/about output:

LOCAL:
Environment:
Redmine version 2.3.1.stable
Ruby version 1.9.3 (x86_64-linux)
Rails version 3.2.13
Environment development
Database adapter Mysql2
Redmine plugins:
extended_fields 0.2.1
redmine_extended_watchers 0.0.2
redmine_glossary 0.7.0
redmine_hudson 2.1.1
redmine_importer 1.0
redmine_landing_page 1.0.0
redmine_ldap_sync 1.3.0.stable
redmine_mylyn_connector 2.8.2.stable
redmine_own_time_entries 0.0.2
redmine_plugin_views_revisions 0.0.1
redmine_reminder 0.0.10
redmine_summed_fields 0.0.2
redmine_wktime 1.5
wiki_external_filter 0.0.2

PROD:
Environment:
Redmine version 2.3.1.stable
Ruby version 1.9.3 (i686-linux)
Rails version 3.2.13
Environment development
Database adapter Mysql2
Redmine plugins:
extended_fields 0.2.1
redmine_extended_watchers 0.0.2
redmine_glossary 0.7.0
redmine_hudson 2.1.1
redmine_importer 1.0
redmine_landing_page 1.0.0
redmine_ldap_sync 1.3.0.stable
redmine_mylyn_connector 2.8.2.stable
redmine_own_time_entries 0.0.2
redmine_plugin_views_revisions 0.0.1
redmine_reminder 0.0.10
redmine_summed_fields 0.0.2
redmine_wktime 1.5
wiki_external_filter 0.0.2

The problem seems to concern model classes only.
Any hint why rails behavior is different?

Thank you!