我在Heroku上运行了一个应用程序，有时会出现此错误：
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/path_traversal.rb:16:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/json_csrf.rb:17:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/logger.rb:15:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/commonlogger.rb:20:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/head.rb:9:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/methodoverride.rb:21:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1334:in `block in call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1416:in `synchronize'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/sinatra- 1.3.2/lib/sinatra/base.rb:1334:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/commonlogger.rb:20:in `call'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/connection.rb:80:in `block in pre_process'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/connection.rb:78:in `catch'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/connection.rb:78:in `pre_process'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/connection.rb:53:in `process'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/connection.rb:38:in `receive_data'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run_machine'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/backends/base.rb:63:in `start'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/server.rb:159:in `start'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/controllers/controller.rb:86:in `start'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/runner.rb:185:in `run_command'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/lib/thin/runner.rb:151:in `run!'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/thin-1.4.1/bin/thin:6:in `<top (required)>'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/bin/thin:19:in `load'
2012-10-03T17:01:32+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/bin/thin:19:in `<main>'
那我该怎么办？ ......
编辑：添加gemfile
source :rubygems
# use Heroku Toolbelt instead
# gem "heroku"
# sinatra main library
gem "sinatra"
# sinatra plugin for localization
gem "sinatra-r18n"
gem "resolv-ipv6favor"
# Json
gem "json"
# rack middleware csrf protection
gem "rack_csrf"
# database handler | orm
gem "pg"
gem "sequel"
gem "sequel_sluggable"
gem "unicode_utils"
gem "sanitize"
gem "fog"
gem "mail"
gem "thin"
# Full system log
gem 'remote_syslog_logger'
group :development do
gem "awesome_print"
gem "sinatra-reloader"
gem "sqlite3"
end