Redmine

Could you please attach your error stack trace (see SubmittingBugs).

sorry, yes sure!
here is what i did to produce this error:
i just changed the date format from my localized format "d.m.Y" to "Based on user's language" and saved.
afterwards i tried to reload the activity page of my "inbox" project. see the log below.

thanks,
paul

Processing SettingsController#edit (for MY_IP at 2010-10-24 19:03:29) [POST]
  Parameters: {"commit"=>"Speichern", "action"=>"edit", "authenticity_token"=>"2VcfI7y_CHANGEDABIT_6dvrPRz8xzCs=", "settings"=>{"user_format"=>"firstname_lastname", "start_of_week"=>"1", "date_format"=>"", "default_language"=>"de", "gravatar_default"=>"", "gravatar_enabled"=>"1", "time_format"=>"%H:%M", "ui_theme"=>"basecamp"}, "controller"=>"settings", "tab"=>"display"}
Settings cache cleared.
Redirected to https://MY_SERVER.COM/settings/edit?tab=display
Completed in 150ms (DB: 113) | 302 Found [https://MY_SERVER.COM/settings/edit?tab=display]

Processing SettingsController#edit (for MY_IP at 2010-10-24 19:03:30) [GET]
  Parameters: {"action"=>"edit", "controller"=>"settings", "tab"=>"display"}
Rendering template within layouts/admin
Rendering settings/edit
Completed in 244ms (View: 213, DB: 28) | 200 OK [https://MY_SERVER.COM/settings/edit?tab=display]

Processing ProjectsController#activity (for MY_IP at 2010-10-24 19:03:34) [GET]
  Parameters: {"action"=>"activity", "id"=>"inbox", "controller"=>"projects"}
Rendering template within layouts/base
Rendering projects/activity

ActionView::TemplateError (missing interpolation argument in "%{count}.%m.%Y" ({:object=>Sat, 25 Sep 2010} given)) on line #2 of app/views/projects/activity.rhtml:
1: <h2><%= @author.nil? ? l(:label_activity) : l(:label_user_activity, link_to_user(@author)) %></h2>
2: <p class="subtitle"><%= l(:label_date_from_to, :start => format_date(@date_to - @days), :end => format_date(@date_to-1)) %></p>
3: 
4: <div id="activity">
5: <% @events_by_day.keys.sort.reverse.each do |day| %>

    /usr/lib/ruby/gems/1.8/gems/i18n-0.4.1/lib/i18n/backend/base.rb:186:in `interpolate_without_deprecated_syntax'
    /usr/lib/ruby/gems/1.8/gems/i18n-0.4.1/lib/i18n/backend/base.rb:49:in `translate'
    /usr/lib/ruby/gems/1.8/gems/i18n-0.4.1/lib/i18n.rb:152:in `t'
    /usr/lib/ruby/gems/1.8/gems/i18n-0.4.1/lib/i18n/backend/base.rb:62:in `localize'
    /usr/lib/ruby/gems/1.8/gems/i18n-0.4.1/lib/i18n.rb:231:in `l'
    lib/redmine/i18n.rb:40:in `format_date'
    app/views/projects/activity.rhtml:2:in `_run_rhtml_app47views47projects47activity46rhtml'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/rack/request_handler.rb:92:in `process_request'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_request_handler.rb:210:in `main_loop'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/railz/application_spawner.rb:441:in `start_request_handler'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/railz/application_spawner.rb:381:in `handle_spawn_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/utils.rb:252:in `safe_fork'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/railz/application_spawner.rb:377:in `handle_spawn_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:352:in `__send__'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:352:in `main_loop'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:163:in `start'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/railz/application_spawner.rb:222:in `start'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/spawn_manager.rb:253:in `spawn_rails_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server_collection.rb:126:in `lookup_or_add'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/spawn_manager.rb:247:in `spawn_rails_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server_collection.rb:80:in `synchronize'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server_collection.rb:79:in `synchronize'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/spawn_manager.rb:246:in `spawn_rails_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/spawn_manager.rb:145:in `spawn_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/spawn_manager.rb:278:in `handle_spawn_application'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:352:in `__send__'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:352:in `main_loop'
    /usr/local/appserver/mod_rails/lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously'

Rendering /PATH_TO_MY_INSTALLATION/public/500.html (500 Internal Server Error)

Are you using 1.0.2 stable release?

yes, i do.