I know, so many people ask this same question, but none of the answers are working for me. Hopefully someone with more experience can help. I am using Devise in this application, if that helps.
When I run heroku ps:
=== web (Free): bin/rails server -p $PORT -e $RAILS_ENV
web.1: up 2015/11/25 02:39:53 (~ 26m ago)
Heroku Log:
2015-11-24T22:05:07.993413+00:00 heroku[slug-compiler]: Slug compilation started
2015-11-24T22:05:07.993428+00:00 heroku[slug-compiler]: Slug compilation finished
2015-11-24T22:05:12.519003+00:00 heroku[web.1]: Starting process with command `bin/rails server -p 32783 -e production`
2015-11-24T22:05:17.529304+00:00 app[web.1]: [2015-11-24 22:05:17] INFO WEBrick 1.3.1
2015-11-24T22:05:17.529328+00:00 app[web.1]: [2015-11-24 22:05:17] INFO ruby 2.0.0 (2015-04-13) [x86_64-linux]
2015-11-24T22:05:17.529573+00:00 app[web.1]: [2015-11-24 22:05:17] INFO WEBrick::HTTPServer#start: pid=3 port=32783
2015-11-24T22:05:17.734507+00:00 heroku[web.1]: State changed from starting to up
2015-11-24T22:08:42.923437+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=43d6d58c-398e-458f-b9d5-d8c573663ef1 fwd="74.70.151.189" dyno=web.1 connect=0ms service=76ms status=500 bytes=1754
2015-11-24T22:08:43.081200+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=fast-plains-8055.herokuapp.com request_id=3abfe83b-7381-4f1b-b901-b7e45ad7a56b fwd="74.70.151.189" dyno=web.1 connect=0ms service=3ms status=200 bytes=228
2015-11-24T22:09:58.449471+00:00 heroku[api]: Starting process with command `db:migrate` by guildconcept@gmail.com
2015-11-24T22:10:00.441658+00:00 heroku[run.1339]: Awaiting client
2015-11-24T22:10:00.463935+00:00 heroku[run.1339]: Starting process with command `db:migrate`
2015-11-24T22:10:00.803616+00:00 heroku[run.1339]: State changed from starting to up
2015-11-24T22:10:02.467681+00:00 heroku[run.1339]: State changed from up to complete
2015-11-24T22:10:02.454690+00:00 heroku[run.1339]: Process exited with status 127
2015-11-24T22:10:11.644955+00:00 heroku[api]: Starting process with command `bundle exec rake db:migrate` by guildconcept@gmail.com
2015-11-24T22:10:13.866452+00:00 heroku[run.4044]: Awaiting client
2015-11-24T22:10:13.906184+00:00 heroku[run.4044]: Starting process with command `bundle exec rake db:migrate`
2015-11-24T22:10:14.244007+00:00 heroku[run.4044]: State changed from starting to up
2015-11-24T22:10:19.778358+00:00 heroku[run.4044]: Process exited with status 0
2015-11-24T22:10:19.767955+00:00 heroku[run.4044]: State changed from up to complete
2015-11-24T22:11:04.093611+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=6f5ee2ef-10e6-446d-97af-69749fd3c7a5 fwd="74.70.151.189" dyno=web.1 connect=1ms service=8ms status=500 bytes=1754
2015-11-24T22:11:04.287865+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=fast-plains-8055.herokuapp.com request_id=b503038f-9174-4cd2-904e-3391ced7fcb6 fwd="74.70.151.189" dyno=web.1 connect=1ms service=3ms status=200 bytes=228
2015-11-24T22:11:05.000050+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=b24a20fd-63bd-4b95-b56e-6e22ee4a4e15 fwd="74.70.151.189" dyno=web.1 connect=1ms service=8ms status=500 bytes=1754
2015-11-24T22:11:05.204728+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=fast-plains-8055.herokuapp.com request_id=c1340dca-2a8f-468a-a155-af24e994c09c fwd="74.70.151.189" dyno=web.1 connect=2ms service=45ms status=200 bytes=228
2015-11-24T22:11:29.626953+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=ecb2067b-26dc-40c8-b527-e1a2d8916df1 fwd="74.70.151.189" dyno=web.1 connect=1ms service=10ms status=500 bytes=1754
2015-11-24T22:14:38.706423+00:00 heroku[api]: Starting process with command `db:migrate` by guildconcept@gmail.com
2015-11-24T22:14:41.036756+00:00 heroku[run.3858]: Starting process with command `db:migrate`
2015-11-24T22:14:41.003571+00:00 heroku[run.3858]: Awaiting client
2015-11-24T22:14:41.529782+00:00 heroku[run.3858]: State changed from starting to up
2015-11-24T22:14:43.490006+00:00 heroku[run.3858]: Process exited with status 127
2015-11-24T22:14:54.658801+00:00 heroku[api]: Starting process with command `bundle exec rake db:migrate` by guildconcept@gmail.com
2015-11-24T22:14:56.424572+00:00 heroku[run.3306]: Awaiting client
2015-11-24T22:14:56.441974+00:00 heroku[run.3306]: Starting process with command `bundle exec rake db:migrate`
2015-11-24T22:14:43.508096+00:00 heroku[run.3858]: State changed from up to complete
2015-11-24T22:14:56.762584+00:00 heroku[run.3306]: State changed from starting to up
2015-11-24T22:15:00.143588+00:00 heroku[run.3306]: Process exited with status 0
2015-11-24T22:15:00.103040+00:00 heroku[run.3306]: State changed from up to complete
2015-11-24T22:17:37.380714+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=f1cd1525-7697-4bba-adec-bb5436af542f fwd="74.70.151.189" dyno=web.1 connect=0ms service=10ms status=500 bytes=1754
2015-11-24T22:17:37.579185+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=fast-plains-8055.herokuapp.com request_id=9099fa00-7526-433b-8191-078b72a54c8b fwd="74.70.151.189" dyno=web.1 connect=1ms service=4ms status=304 bytes=133
2015-11-24T22:51:40.649681+00:00 heroku[web.1]: Idling
2015-11-24T22:51:40.650445+00:00 heroku[web.1]: State changed from up to down
2015-11-24T22:51:46.152454+00:00 heroku[web.1]: Stopping all processes with SIGTERM
2015-11-24T22:51:47.371522+00:00 app[web.1]: [2015-11-24 22:51:47] FATAL SignalException: SIGTERM
2015-11-24T22:51:47.371527+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:170:in `select'
2015-11-24T22:51:47.371530+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:170:in `block in start'
2015-11-24T22:51:47.371530+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:32:in `start'
2015-11-24T22:51:47.371531+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:160:in `start'
2015-11-24T22:51:47.371533+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/server.rb:80:in `start'
2015-11-24T22:51:47.371532+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/rack-1.6.4/lib/rack/handler/webrick.rb:34:in `run'
2015-11-24T22:51:47.371534+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:80:in `block in server'
2015-11-24T22:51:47.371532+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/rack-1.6.4/lib/rack/server.rb:286:in `start'
2015-11-24T22:51:47.371538+00:00 app[web.1]: bin/rails:9:in `<main>'
2015-11-24T22:51:47.371664+00:00 app[web.1]: [2015-11-24 22:51:47] INFO WEBrick::HTTPServer#start done.
2015-11-24T22:51:47.371534+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:75:in `tap'
2015-11-24T22:51:47.371536+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
2015-11-24T22:51:47.371606+00:00 app[web.1]: [2015-11-24 22:51:47] INFO going to shutdown ...
2015-11-24T22:51:47.412305+00:00 app[web.1]: => Booting WEBrick
2015-11-24T22:51:47.371535+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:75:in `server'
2015-11-24T22:51:47.412309+00:00 app[web.1]: => Rails 4.2.4 application starting in production on http://0.0.0.0:32783
2015-11-24T22:51:47.412311+00:00 app[web.1]: => Ctrl-C to shutdown server
2015-11-24T22:51:47.371537+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands.rb:17:in `<top (required)>'
2015-11-24T22:51:47.371538+00:00 app[web.1]: bin/rails:9:in `require'
2015-11-24T22:51:47.412311+00:00 app[web.1]: => Run `rails server -h` for more startup options
2015-11-24T22:51:47.412312+00:00 app[web.1]: Exiting
2015-11-24T22:51:48.125299+00:00 heroku[web.1]: Process exited with status 143
2015-11-24T23:09:53.602567+00:00 heroku[web.1]: Unidling
2015-11-24T23:09:53.602829+00:00 heroku[web.1]: State changed from down to starting
2015-11-24T23:09:55.419638+00:00 heroku[web.1]: Starting process with command `bin/rails server -p 6079 -e production`
2015-11-24T23:09:59.250927+00:00 app[web.1]: [2015-11-24 23:09:59] INFO WEBrick 1.3.1
2015-11-24T23:09:59.250946+00:00 app[web.1]: [2015-11-24 23:09:59] INFO ruby 2.0.0 (2015-04-13) [x86_64-linux]
2015-11-24T23:09:59.259572+00:00 app[web.1]: [2015-11-24 23:09:59] INFO WEBrick::HTTPServer#start: pid=3 port=6079
2015-11-24T23:10:00.706946+00:00 heroku[router]: at=info method=GET path="/" host=fast-plains-8055.herokuapp.com request_id=6330fb41-d30c-48d1-86a3-b2fdfbfb983f fwd="74.70.151.189" dyno=web.1 connect=0ms service=48ms status=500 bytes=1754
2015-11-24T23:09:59.641116+00:00 heroku[web.1]: State changed from starting to up
2015-11-24T23:10:00.900587+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=fast-plains-8055.herokuapp.com request_id=fac0f43d-0385-445d-8325-29cc14c68ad1 fwd="74.70.151.189" dyno=web.1 connect=0ms service=7ms status=200 bytes=228
2015-11-24T23:43:31.043394+00:00 heroku[web.1]: Idling
2015-11-24T23:43:31.043394+00:00 heroku[web.1]: State changed from up to down
2015-11-24T23:43:33.423424+00:00 heroku[web.1]: Stopping all processes with SIGTERM
2015-11-24T23:43:34.039752+00:00 app[web.1]: [2015-11-24 23:43:34] FATAL SignalException: SIGTERM
2015-11-24T23:43:34.039757+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:170:in `select'
2015-11-24T23:43:34.039759+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:170:in `block in start'
2015-11-24T23:43:34.039760+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:32:in `start'
2015-11-24T23:43:34.039761+00:00 app[web.1]: /app/vendor/ruby-2.0.0/lib/ruby/2.0.0/webrick/server.rb:160:in `start'
2015-11-24T23:43:34.039762+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/rack-1.6.4/lib/rack/handler/webrick.rb:34:in `run'
2015-11-24T23:43:34.039763+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/rack-1.6.4/lib/rack/server.rb:286:in `start'
2015-11-24T23:43:34.039764+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/server.rb:80:in `start'
2015-11-24T23:43:34.039765+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:80:in `block in server'
2015-11-24T23:43:34.039766+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:75:in `tap'
2015-11-24T23:43:34.039767+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:75:in `server'
2015-11-24T23:43:34.039768+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
2015-11-24T23:43:34.039768+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/railties-4.2.4/lib/rails/commands.rb:17:in `<top (required)>'
2015-11-24T23:43:34.039770+00:00 app[web.1]: bin/rails:9:in `require'
2015-11-24T23:43:34.039770+00:00 app[web.1]: bin/rails:9:in `<main>'
2015-11-24T23:43:34.039854+00:00 app[web.1]: [2015-11-24 23:43:34] INFO going to shutdown ...
2015-11-24T23:43:34.039919+00:00 app[web.1]: [2015-11-24 23:43:34] INFO WEBrick::HTTPServer#start done.
2015-11-24T23:43:34.070390+00:00 app[web.1]: => Booting WEBrick
2015-11-24T23:43:34.070396+00:00 app[web.1]: => Run `rails server -h` for more startup options
2015-11-24T23:43:34.070395+00:00 app[web.1]: => Rails 4.2.4 application starting in production on http://0.0.0.0:6079
2015-11-24T23:43:34.070397+00:00 app[web.1]: => Ctrl-C to shutdown server
2015-11-24T23:43:34.070398+00:00 app[web.1]: Exiting
2015-11-24T23:43:34.912741+00:00 heroku[web.1]: Process exited with status 143
