我在 Heroku 上有一个现有的 rails (3.2.14) 项目，需要迁移数据库。但是当我尝试运行操作时：
heroku run rake db:migrate
我只是得到一个错误。当我们遇到 R99 错误（下面的 Heroku 日志）时，这意味着平台问题。但是 heroku 状态页面对任何问题都保持沉默。这是我的--trace：
$ heroku run rake db:migrate --trace
Running `rake db:migrate --trace` attached to terminal... up, run.4543
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
Connecting to database specified by DATABASE_URL
rake aborted!
SIGTERM
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:653:in `select'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:653:in `request'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:506:in `block in each_resource'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1023:in `block (3 levels) in resolv'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1021:in `each'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1021:in `block (2 levels) in resolv'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1020:in `each'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1020:in `block in resolv'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1018:in `each'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:1018:in `resolv'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:498:in `each_resource'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:391:in `each_address'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:115:in `block in each_address'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:114:in `each'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:114:in `each_address'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:92:in `getaddress'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/resolv.rb:43:in `getaddress'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm- 3.6.7.152/lib/new_relic/control/server_methods.rb:70:in `resolve_ip_address'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/control/server_methods.rb:59:in `convert_to_ip_address'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/control/server_methods.rb:45:in `server_from_host'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/control/server_methods.rb:19:in `server'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/agent/new_relic_service.rb:28:in `initialize'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/agent/agent.rb:39:in `new'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/agent/agent.rb:39:in `initialize'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/agent/agent.rb:70:in `new'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/agent/agent.rb:70:in `instance'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/new_relic/control/instance_methods.rb:75:in `init_plugin'
/app/vendor/bundle/ruby/1.9.1/gems/newrelic_rpm-3.6.7.152/lib/newrelic_rpm.rb:40:in `block in <class:Railtie>'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/initializable.rb:30:in `instance_exec'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/initializable.rb:30:in `run'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/initializable.rb:55:in `block in run_initializers'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/initializable.rb:54:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/initializable.rb:54:in `run_initializers'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/application.rb:136:in `initialize!'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/railtie/configurable.rb:30:in `method_missing'
/app/config/environment.rb:5:in `<top (required)>'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/dependencies.rb:251:in `require'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/dependencies.rb:251:in `block in require'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/dependencies.rb:236:in `load_dependency'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/dependencies.rb:251:in `require'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/application.rb:103:in `require_environment!'
/app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.14/lib/rails/application.rb:305:in `block (2 levels) in initialize_tasks'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:236:in `call'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:236:in `block in execute'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:231:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:231:in `execute'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:175:in `block in invoke_with_call_chain'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:197:in `block in invoke_prerequisites'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:195:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:195:in `invoke_prerequisites'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:174:in `block in invoke_with_call_chain'
/app/vendor/ruby-1.9.3/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/task.rb:161:in `invoke'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:149:in `invoke_task'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:106:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:106:in `block in top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:115:in `run_with_threads'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:100:in `top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:78:in `block in run'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:75:in `run'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.1.0/bin/rake:33:in `<top (required)>'
/app/vendor/bundle/ruby/1.9.1/bin/rake:23:in `load'
/app/vendor/bundle/ruby/1.9.1/bin/rake:23:in `<main>'
Tasks: TOP => db:migrate => environment
和heroku日志：
2013-10-31T11:44:20+00:00 heroku[slug-compiler]: Slug compilation started
2013-10-31T11:44:52.399896+00:00 heroku[api]: Deploy b311a8a by ex@gmail.com
2013-10-31T11:44:52.588630+00:00 heroku[api]: Release v10 created by ex@gmail.com
2013-10-31T11:44:52+00:00 heroku[slug-compiler]: Slug compilation finished
2013-10-31T11:44:53.144455+00:00 heroku[web.1]: State changed from up to starting
2013-10-31T11:44:55.603062+00:00 heroku[web.1]: Stopping all processes with SIGTERM
2013-10-31T11:44:57.453462+00:00 heroku[web.1]: Process exited with status 0
2013-10-31T11:45:00.188675+00:00 heroku[web.1]: Starting process with command `bundle exec thin start -R config.ru -e $RAILS_ENV -p 32970`
2013-10-31T11:45:07.793567+00:00 app[web.1]: /app/bin/wkhtmltopdf-amd64
2013-10-31T11:45:08.480104+00:00 app[web.1]: Connecting to database specified by DATABASE_URL
2013-10-31T11:45:09.700798+00:00 app[web.1]: >> Maximum connections set to 1024
2013-10-31T11:45:09.700798+00:00 app[web.1]: >> Listening on 0.0.0.0:32970, CTRL+C to stop
2013-10-31T11:45:09.700798+00:00 app[web.1]: >> Thin web server (v1.5.1 codename Straight Razor)
2013-10-31T11:45:09.760592+00:00 heroku[web.1]: State changed from starting to up
2013-10-31T11:45:43.023857+00:00 heroku[api]: Starting process with command `bundle exec rake db:migrate` by ex@gmail.com
2013-10-31T11:45:47.706892+00:00 heroku[run.7727]: Awaiting client
2013-10-31T11:45:55.105222+00:00 heroku[run.7727]: State changed from starting to up
2013-10-31T11:45:57.322699+00:00 heroku[run.7727]: Error R99 (Platform error) -> Failed to launch the dyno within 10 seconds
2013-10-31T11:45:57.323016+00:00 heroku[run.7727]: Stopping process with SIGKILL
2013-10-31T11:45:57.368215+00:00 heroku[run.7727]: State changed from up to complete
2013-10-31T11:46:04.657083+00:00 heroku[run.7727]: Starting process with command `bundle exec rake db:migrate`
2013-10-31T11:48:08.633448+00:00 heroku[run.7727]: Stopping all processes with SIGTERM
2013-10-31T11:48:18.781513+00:00 heroku[run.7727]: Stopping remaining processes with SIGKILL
2013-10-31T11:48:18.781292+00:00 heroku[run.7727]: Error R12 (Exit timeout) -> At least one process failed to exit within 10 seconds of SIGTERM
2013-10-31T11:48:19.712818+00:00 heroku[run.7727]: Client connection closed. Sending SIGHUP to all processes
2013-10-31T11:48:21.005685+00:00 heroku[run.7727]: Process exited with status 137