Redmine

i upgraded from redmine-2.2.1 to redmine-2.3.0 by folowing the upgrade-instruction but since then i'm unable to edit the settings …

Started GET "/settings" for 79.230.95.56 at Mon Apr 29 10:20:35 +0200 2013
Processing by SettingsController#index as HTML
  Current user: marco.tralles (id=1)
  Rendered settings/_general.html.erb (6.4ms)
  Rendered settings/_display.html.erb (9.1ms)
  Rendered settings/_authentication.html.erb (5.1ms)
  Rendered common/_tabs.html.erb (25.0ms)
  Rendered settings/edit.html.erb within layouts/admin (25.5ms)
Completed 500 Internal Server Error in 39ms

ActionView::Template::Error (undefined method `jsonp_enabled?' for #<Class:0x7f5e510eadd8>):
    20: 
    21: <p><%= setting_check_box :rest_api_enabled %></p>
    22: 
    23: <p><%= setting_check_box :jsonp_enabled %></p>
    24: </div>
    25: 
    26: <fieldset class="box">
  app/helpers/settings_helper.rb:77:in `send'
  app/helpers/settings_helper.rb:77:in `setting_check_box'
  app/views/settings/_authentication.html.erb:23:in `_app_views_settings__authentication_html_erb__1288271338_70021525672740'
  app/views/settings/_authentication.html.erb:1:in `_app_views_settings__authentication_html_erb__1288271338_70021525672740'
  app/views/common/_tabs.html.erb:24:in `_app_views_common__tabs_html_erb___2143840881_70021529800140'
  app/views/common/_tabs.html.erb:23:in `each'
  app/views/common/_tabs.html.erb:23:in `_app_views_common__tabs_html_erb___2143840881_70021529800140'
  app/helpers/application_helper.rb:271:in `render_tabs'
  app/views/settings/edit.html.erb:3:in `_app_views_settings_edit_html_erb___34582695_70021529858860'
  app/controllers/settings_controller.rb:28:in `index'