我刚刚将应用更新到rails 3.0.15，我不确定这是否是相关位，但我现在在运行服务器后立即收到struct Arel::Attributes::Attribute not compatible (struct size differs)错误。
日志显示：
tarted GET "/" for 127.0.0.1 at 2012-06-14 10:34:09 -0400
TypeError (struct Arel::Attributes::Attribute not compatible (struct size differs)):
Rendered gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.3ms)
SQL (1.9ms) describe `groups_users`
Rendered gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (239.8ms)
Rendered gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (244.9ms)
这个问题似乎只有在我使用某个循环回localhost的网址时才会发生，即live.dev:3000，只需说localhost:3000或其他循环网址就可以了。
这是应用程序跟踪
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/session_store.rb:58:in `load'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/session_store.rb:58:in `unmarshal'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/session_store.rb:131:in `data'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/session_store.rb:298:in `block in get_session'
gems/ruby/1.9.1/gems/activesupport-3.0.15/lib/active_support/benchmarkable.rb:55:in `silence'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/session_store.rb:294:in `get_session'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:195:in `block in load_session'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:223:in `stale_session_check!'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:193:in `load_session'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:121:in `load!'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:113:in `load_for_read!'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:53:in `[]'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/flash.rb:178:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/cookies.rb:302:in `call'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/query_cache.rb:32:in `block in call'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/query_cache.rb:12:in `cache'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/query_cache.rb:31:in `call'
gems/ruby/1.9.1/gems/activerecord-3.0.15/lib/active_record/connection_adapters/abstract/connection_pool.rb:354:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/callbacks.rb:46:in `block in call'
gems/ruby/1.9.1/gems/activesupport-3.0.15/lib/active_support/callbacks.rb:416:in `_run_call_callbacks'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/callbacks.rb:44:in `call'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/sendfile.rb:106:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
gems/ruby/1.9.1/gems/railties-3.0.15/lib/rails/rack/logger.rb:13:in `call'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/runtime.rb:17:in `call'
gems/ruby/1.9.1/gems/activesupport-3.0.15/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/lock.rb:13:in `block in call'
<internal:prelude>:10:in `synchronize'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/lock.rb:13:in `call'
gems/ruby/1.9.1/gems/actionpack-3.0.15/lib/action_dispatch/middleware/static.rb:30:in `call'
gems/ruby/1.9.1/gems/railties-3.0.15/lib/rails/application.rb:168:in `call'
gems/ruby/1.9.1/gems/railties-3.0.15/lib/rails/application.rb:77:in `method_missing'
gems/ruby/1.9.1/gems/railties-3.0.15/lib/rails/rack/log_tailer.rb:14:in `call'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/content_length.rb:13:in `call'
gems/ruby/1.9.1/gems/rack-1.2.5/lib/rack/handler/webrick.rb:52:in `service'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'