Redmine

About your application's environment
Ruby version 1.8.7 (x86_64-linux)
RubyGems version 1.3.7
Rack version 1.1
Rails version 2.3.5
Active Record version 2.3.5
Active Resource version 2.3.5
Action Mailer version 2.3.5
Active Support version 2.3.5
Edge Rails revision unknown
Application root /usr/share/redmine
Environment production
Database adapter postgresql
Database schema version 20110201111915

About your Redmine plugins
Redmine Opensearch plugin 0.1
Redcase 1.0 alpha 0.144
Redmine Google Docs Plugin plugin 0.0.1
Redmine Graphs plugin 0.1.0

svn, version 1.6.12 (r955767)

production.log:

Processing RepositoriesController#show (for 192.168.0.19 at 2011-03-16 17:53:24) [GET]
Parameters: {"action"=>"show", "id"=>"support", "controller"=>"repositories"}
NoMethodError (undefined method `left' for nil:NilClass):
/usr/lib/ruby/1.8/active_record/associations/association_proxy.rb:217:in `send'
/usr/lib/ruby/1.8/active_record/associations/association_proxy.rb:217:in `method_missing'
app/models/changeset.rb:186:in `find_referenced_issue_by_id'
app/models/changeset.rb:125:in `scan_comment_for_issue_ids'
app/models/changeset.rb:124:in `each'
app/models/changeset.rb:124:in `scan_comment_for_issue_ids'
app/models/changeset.rb:120:in `scan'
app/models/changeset.rb:120:in `scan_comment_for_issue_ids'
app/models/changeset.rb:95:in `after_create'
/usr/lib/ruby/1.8/active_record/callbacks.rb:347:in `send'
/usr/lib/ruby/1.8/active_record/callbacks.rb:347:in `callback'
/usr/lib/ruby/1.8/active_record/callbacks.rb:267:in `create'
/usr/lib/ruby/1.8/active_record/base.rb:2874:in `create_or_update_without_callbacks'
/usr/lib/ruby/1.8/active_record/callbacks.rb:250:in `create_or_update'
/usr/lib/ruby/1.8/active_record/base.rb:2538:in `save_without_validation'
/usr/lib/ruby/1.8/active_record/validations.rb:1078:in `save_without_dirty'
/usr/lib/ruby/1.8/active_record/dirty.rb:79:in `save_without_transactions'
/usr/lib/ruby/1.8/active_record/transactions.rb:229:in `send'
/usr/lib/ruby/1.8/active_record/transactions.rb:229:in `with_transaction_returning_status'
/usr/lib/ruby/1.8/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction'
/usr/lib/ruby/1.8/active_record/transactions.rb:182:in `transaction'
/usr/lib/ruby/1.8/active_record/transactions.rb:228:in `with_transaction_returning_status'
/usr/lib/ruby/1.8/active_record/transactions.rb:196:in `save'
/usr/lib/ruby/1.8/active_record/transactions.rb:208:in `rollback_active_record_state!'
/usr/lib/ruby/1.8/active_record/transactions.rb:196:in `save'
/usr/lib/ruby/1.8/active_record/base.rb:723:in `create'
app/models/repository/subversion.rb:59:in `fetch_changesets'
/usr/lib/ruby/1.8/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction'
/usr/lib/ruby/1.8/active_record/transactions.rb:182:in `transaction'
/usr/lib/ruby/1.8/active_record/transactions.rb:188:in `transaction'
app/models/repository/subversion.rb:58:in `fetch_changesets'
app/models/repository/subversion.rb:57:in `reverse_each'
app/models/repository/subversion.rb:57:in `fetch_changesets'
/usr/lib/ruby/1.8/active_record/associations/association_proxy.rb:217:in `send'
/usr/lib/ruby/1.8/active_record/associations/association_proxy.rb:217:in `method_missing'
app/controllers/repositories_controller.rb:77:in `show'
/usr/lib/ruby/1.8/action_controller/base.rb:1331:in `send'
/usr/lib/ruby/1.8/action_controller/base.rb:1331:in `perform_action_without_filters'
/usr/lib/ruby/1.8/action_controller/filters.rb:617:in `call_filters'
/usr/lib/ruby/1.8/action_controller/filters.rb:610:in `perform_action_without_benchmark'
/usr/lib/ruby/1.8/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/usr/lib/ruby/1.8/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/usr/lib/ruby/1.8/action_controller/rescue.rb:160:in `perform_action_without_flash'
/usr/lib/ruby/1.8/action_controller/flash.rb:146:in `perform_action'
/usr/lib/ruby/1.8/action_controller/base.rb:532:in `send'
/usr/lib/ruby/1.8/action_controller/base.rb:532:in `process_without_filters'
/usr/lib/ruby/1.8/action_controller/filters.rb:606:in `process'
/usr/lib/ruby/1.8/action_controller/base.rb:391:in `process'
/usr/lib/ruby/1.8/action_controller/base.rb:386:in `call'
/usr/lib/ruby/1.8/action_controller/routing/route_set.rb:437:in `call'
/usr/lib/ruby/1.8/action_controller/dispatcher.rb:87:in `dispatch'
/usr/lib/ruby/1.8/action_controller/dispatcher.rb:121:in `_call'
/usr/lib/ruby/1.8/action_controller/dispatcher.rb:130:in `build_middleware_stack'
/usr/lib/ruby/1.8/active_record/query_cache.rb:29:in `call'
/usr/lib/ruby/1.8/active_record/query_cache.rb:29:in `call'
/usr/lib/ruby/1.8/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache'
/usr/lib/ruby/1.8/active_record/query_cache.rb:9:in `cache'
/usr/lib/ruby/1.8/active_record/query_cache.rb:28:in `call'
/usr/lib/ruby/1.8/active_record/connection_adapters/abstract/connection_pool.rb:361:in `call'
/usr/lib/ruby/1.8/action_controller/string_coercion.rb:25:in `call'
/usr/lib/ruby/1.8/rack/head.rb:9:in `call'
/usr/lib/ruby/1.8/rack/methodoverride.rb:24:in `call'
/usr/lib/ruby/1.8/action_controller/params_parser.rb:15:in `call'
/usr/lib/ruby/1.8/action_controller/session/cookie_store.rb:93:in `call'
/usr/lib/ruby/1.8/action_controller/failsafe.rb:26:in `call'
/usr/lib/ruby/1.8/rack/lock.rb:11:in `call'
/usr/lib/ruby/1.8/rack/lock.rb:11:in `synchronize'
/usr/lib/ruby/1.8/rack/lock.rb:11:in `call'
/usr/lib/ruby/1.8/action_controller/dispatcher.rb:106:in `call'
/usr/lib/ruby/1.8/phusion_passenger/rack/request_handler.rb:92:in `process_request'
/usr/lib/ruby/1.8/phusion_passenger/abstract_request_handler.rb:207:in `main_loop'
/usr/lib/ruby/1.8/phusion_passenger/railz/application_spawner.rb:418:in `start_request_handler'
/usr/lib/ruby/1.8/phusion_passenger/railz/application_spawner.rb:418:in `start_request_handler'
/usr/lib/ruby/1.8/phusion_passenger/railz/application_spawner.rb:358:in `handle_spawn_application'
/usr/lib/ruby/1.8/phusion_passenger/utils.rb:184:in `safe_fork'
/usr/lib/ruby/1.8/phusion_passenger/railz/application_spawner.rb:354:in `handle_spawn_application'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:352:in `__send__'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:352:in `main_loop'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:196:in `start_synchronously'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:163:in `start'
/usr/lib/ruby/1.8/phusion_passenger/railz/application_spawner.rb:213:in `start'
/usr/lib/ruby/1.8/phusion_passenger/spawn_manager.rb:262:in `spawn_rails_application'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server_collection.rb:126:in `lookup_or_add'
/usr/lib/ruby/1.8/phusion_passenger/spawn_manager.rb:256:in `spawn_rails_application'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server_collection.rb:80:in `synchronize'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server_collection.rb:79:in `synchronize'
/usr/lib/ruby/1.8/phusion_passenger/spawn_manager.rb:255:in `spawn_rails_application'
/usr/lib/ruby/1.8/phusion_passenger/spawn_manager.rb:154:in `spawn_application'
/usr/lib/ruby/1.8/phusion_passenger/spawn_manager.rb:287:in `handle_spawn_application'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:352:in `__send__'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:352:in `main_loop'
/usr/lib/ruby/1.8/phusion_passenger/abstract_server.rb:196:in `start_synchronously'
/usr/lib/phusion_passenger/passenger-spawn-server:61

Rendering /usr/share/redmine/public/500.html (500 Internal Server Error)

The symptoms are the same as described here: http://www.redmine.org/boards/2/topics/16046
The patch referenced in that post fixes the problem for me.