RAILS APP : heroku[router]: at=error code=H10 desc="App crashed"

Question

I'm trying to launch my rails app from my local computer to HEROKU. I've searched on stackoverflow but I can't seem to find information about this issue - Some say it's a profile and others say it's a package.json file. None of it actually worked - is there something I'm missing?

Gem File

group :development do 
# Use sqlite3 as the database for Active Record
  gem 'sqlite3'
end

group :production do
  gem 'pg'
  gem 'rails_12factor'
end

Heroku Logs --Tail

2019-05-14T07:31:46.981736+00:00 heroku[web.1]: State changed from crashed to starting
2019-05-14T07:31:50.681385+00:00 heroku[web.1]: Starting process with command `bundle exec rails server thin -p 18879 -e production`
2019-05-14T07:31:55.137458+00:00 heroku[web.1]: State changed from starting to crashed
2019-05-14T07:31:55.106359+00:00 heroku[web.1]: Process exited with status 1
2019-05-14T07:31:55.019384+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:33:in `require': cannot load such file -- thin (LoadError)
2019-05-14T07:31:55.019424+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
2019-05-14T07:31:55.019426+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
2019-05-14T07:31:55.019428+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
2019-05-14T07:31:55.019438+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler/thin.rb:1:in `<top (required)>'
2019-05-14T07:31:55.019440+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
2019-05-14T07:31:55.019446+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
2019-05-14T07:31:55.019448+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
2019-05-14T07:31:55.019450+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
2019-05-14T07:31:55.019451+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
2019-05-14T07:31:55.019453+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
2019-05-14T07:31:55.019458+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
2019-05-14T07:31:55.019460+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
2019-05-14T07:31:55.019467+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler.rb:20:in `const_get'
2019-05-14T07:31:55.019469+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler.rb:20:in `block in get'
2019-05-14T07:31:55.019470+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler.rb:20:in `each'
2019-05-14T07:31:55.019472+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler.rb:20:in `inject'
2019-05-14T07:31:55.019473+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/handler.rb:20:in `get'
2019-05-14T07:31:55.019475+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/rack-2.0.7/lib/rack/server.rb:301:in `server'
2019-05-14T07:31:55.019477+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:105:in `use_puma?'
2019-05-14T07:31:55.019482+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:76:in `print_boot_information'
2019-05-14T07:31:55.019484+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:47:in `start'
2019-05-14T07:31:55.019486+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:147:in `block in perform'
2019-05-14T07:31:55.019487+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `tap'
2019-05-14T07:31:55.019489+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `perform'
2019-05-14T07:31:55.019490+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
2019-05-14T07:31:55.019492+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
2019-05-14T07:31:55.019494+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
2019-05-14T07:31:55.019495+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command/base.rb:65:in `perform'
2019-05-14T07:31:55.019500+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command.rb:46:in `invoke'
2019-05-14T07:31:55.019502+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands.rb:18:in `<top (required)>'
2019-05-14T07:31:55.019504+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
2019-05-14T07:31:55.019505+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
2019-05-14T07:31:55.019507+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
2019-05-14T07:31:55.019508+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
2019-05-14T07:31:55.019510+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
2019-05-14T07:31:55.019512+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
2019-05-14T07:31:55.019513+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
2019-05-14T07:31:55.019515+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
2019-05-14T07:31:55.019522+00:00 app[web.1]: from bin/rails:9:in `<main>'
2019-05-14T07:31:55.022993+00:00 app[web.1]: Exiting
2019-05-14T07:31:56.410195+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=warm-harbor-88564.herokuapp.com request_id=5926f399-ce9e-4671-b545-de0eb7dca827 fwd="66.229.63.152" dyno= connect= service= status=503 bytes= protocol=https
2019-05-14T07:31:57.780810+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=warm-harbor-88564.herokuapp.com request_id=7b9663f4-abe7-4281-a41d-f867dc8e5aad fwd="66.229.63.152" dyno= connect= service= status=503 bytes= protocol=https

Answer 1

The error message

require': cannot load such file -- thin (LoadError) 

indicates that you are trying to load the thin gem in your application but that is is not in your referenced in you Gemfile – Perhaps you installed it manually in your development machine or the code that raises the error runs only on the production environment.

Just add the thin gem to you Gemfile

gem 'thin'

run bundle install again and redeploy the changes to Heroku.