Why doesn't the rails app run on Heroku?

On the application page, the server writes - an error, look in the log file. Where exactly to look in the log file? Googled all the lines with exclamation marks, tried to enter different combinations of characters in the console, recommended in StackOverflow. In general, the error is in place.

Log:

-----> Ruby app detected -----> Compiling Ruby/Rails -----> Using Ruby version: ruby-2.3.1 -----> Installing dependencies using bundler 1.15.2 Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment Warning: the running version of Bundler (1.15.2) is older than the version that created the lockfile (1.15.4). We suggest you upgrade to the latest version of Bundler by running `gem install bundler`. Fetching gem metadata from https://rubygems.org/......... Fetching version metadata from https://rubygems.org/.. Fetching dependency metadata from https://rubygems.org/. Using rake 12.1.0 Using concurrent-ruby 1.0.5 Using i18n 0.8.6 Using minitest 5.10.3 Using thread_safe 0.3.6 Using builder 3.2.3 Using erubi 1.6.1 Using mini_portile2 2.3.0 Using rack 2.0.3 Using nio4r 2.1.0 Using websocket-extensions 0.1.2 Using mime-types-data 3.2016.0521 Using arel 8.0.0 Using babel-source 5.8.35 Using execjs 2.7.0 Using bundler 1.15.2 Using coffee-script-source 1.12.2 Using method_source 0.8.2 Using thor 0.20.0 Fetching daemons 1.2.4 Fetching eventmachine 1.2.5 Using sass 3.4.25 Using multi_json 1.12.2 Using puma 3.10.0 Using rails_serve_static_assets 0.0.5 Using rails_stdout_logging 0.0.5 Using tilt 2.0.8 Using turbolinks-source 5.0.3 Using tzinfo 1.2.3 Using nokogiri 1.8.1 Using rack-test 0.7.0 Using sprockets 3.7.1 Using mime-types 3.1 Using websocket-driver 0.6.5 Using babel-transpiler 0.7.0 Using uglifier 3.2.0 Using coffee-script 2.4.1 Installing daemons 1.2.4 Using rails_12factor 0.0.2 Using turbolinks 5.0.1 Using activesupport 5.1.4 Using loofah 2.0.3 Using mail 2.6.6 Using sprockets-es6 0.9.2 Using rails-dom-testing 2.0.3 Using globalid 0.4.0 Using activemodel 5.1.4 Using jbuilder 2.7.0 Using rails-html-sanitizer 1.0.3 Using activejob 5.1.4 Using activerecord 5.1.4 Using actionview 5.1.4 Using actionpack 5.1.4 Using actioncable 5.1.4 Using actionmailer 5.1.4 Using railties 5.1.4 Using sprockets-rails 3.2.1 Using coffee-rails 4.2.2 Using foundation-rails 6.4.1.2 Using jquery-rails 4.3.1 Using rails 5.1.4 Using sass-rails 5.0.6 Installing eventmachine 1.2.5 with native extensions Fetching thin 1.7.2 Installing thin 1.7.2 with native extensions Bundle complete! 21 Gemfile dependencies, 62 gems now installed. Gems in the groups development and test were not installed. Bundled gems are installed into ./vendor/bundle. The latest bundler is 1.16.0.pre.2, but you are currently running 1.15.2. To update, run `gem install bundler --pre` Bundle completed (14.14s) Cleaning up the bundler cache. Warning: the running version of Bundler (1.15.2) is older than the version that created the lockfile (1.15.4). We suggest you upgrade to the latest version of Bundler by running `gem install bundler`. The latest bundler is 1.16.0.pre.2, but you are currently running 1.15.2. To update, run `gem install bundler --pre` -----> Installing node-v6.11.1-linux-x64 Detected manifest file, assuming assets were compiled locally ###### WARNING: No Procfile detected, using the default web server. We recommend explicitly declaring how to boot your server process via a Procfile. https://devcenter.heroku.com/articles/ruby-default-web-server -----> Discovering process types Procfile declares types -> (none) Default types for buildpack -> console, rake, web, worker -----> Compressing... Done: 38.3M -----> Launching... Released v6 https://shrouded-escarpment-49254.herokuapp.com/ deployed to Heroku 

But heroku logs:

 2017-09-20T08:42:58.071079+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/launcher.rb:183:in `run' 2017-09-20T08:42:58.071080+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/cli.rb:77:in `run' 2017-09-20T08:42:58.071081+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/bin/puma:10:in `<top (required)>' 2017-09-20T08:42:58.071081+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/bin/puma:23:in `load' 2017-09-20T08:42:58.071101+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/bin/puma:23:in `<top (required)>' 2017-09-20T08:42:58.332980+00:00 heroku[web.1]: State changed from starting to crashed 2017-09-20T08:42:58.334813+00:00 heroku[web.1]: State changed from crashed to starting 2017-09-20T08:42:58.315653+00:00 heroku[web.1]: Process exited with status 1 2017-09-20T08:43:01.417653+00:00 heroku[web.1]: Starting process with command `bundle exec puma -t 5:5 -p ${PORT:-3000} -e ${RACK_ENV:-development}` 2017-09-20T08:43:04.219128+00:00 app[web.1]: Puma starting in single mode... 2017-09-20T08:43:04.219179+00:00 app[web.1]: * Version 3.10.0 (ruby 2.3.1-p112), codename: Russell's Teapot 2017-09-20T08:43:04.219180+00:00 app[web.1]: * Min threads: 5, max threads: 5 2017-09-20T08:43:04.219181+00:00 app[web.1]: * Environment: production 2017-09-20T08:43:06.882741+00:00 app[web.1]: ! Unable to load application: Gem::LoadError: Specified 'sqlite3' for database adapter, but the gem is not loaded. Add `gem 'sqlite3'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). 2017-09-20T08:43:06.882808+00:00 app[web.1]: bundler: failed to load command: puma (/app/vendor/bundle/ruby/2.3.0/bin/puma) 2017-09-20T08:43:06.882885+00:00 app[web.1]: Gem::LoadError: Specified 'sqlite3' for database adapter, but the gem is not loaded. Add `gem 'sqlite3'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). 2017-09-20T08:43:06.882887+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/connection_adapters/connection_specification.rb:188:in `rescue in spec' 2017-09-20T08:43:06.882888+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/connection_adapters/connection_specification.rb:185:in `spec' 2017-09-20T08:43:06.882889+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:880:in `establish_connection' 2017-09-20T08:43:06.882891+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/connection_handling.rb:58:in `establish_connection' 2017-09-20T08:43:06.882893+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:69:in `instance_eval' 2017-09-20T08:43:06.882892+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/railtie.rb:124:in `block (2 levels) in <class:Railtie>' 2017-09-20T08:43:06.882893+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:69:in `block in execute_hook' 2017-09-20T08:43:06.882894+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:60:in `with_execution_control' 2017-09-20T08:43:06.882895+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:50:in `block in run_load_hooks' 2017-09-20T08:43:06.882895+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:65:in `execute_hook' 2017-09-20T08:43:06.882897+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:49:in `each' 2017-09-20T08:43:06.882898+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/lazy_load_hooks.rb:49:in `run_load_hooks' 2017-09-20T08:43:06.882898+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/base.rb:326:in `<module:ActiveRecord>' 2017-09-20T08:43:06.882899+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/base.rb:25:in `<top (required)>' 2017-09-20T08:43:06.882900+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `require' 2017-09-20T08:43:06.882901+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `block in require' 2017-09-20T08:43:06.882901+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:258:in `load_dependency' 2017-09-20T08:43:06.882902+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `require' 2017-09-20T08:43:06.882903+00:00 app[web.1]: /app/app/models/application_record.rb:1:in `<top (required)>' 2017-09-20T08:43:06.882905+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `block in require' 2017-09-20T08:43:06.882904+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `require' 2017-09-20T08:43:06.882906+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:292:in `require' 2017-09-20T08:43:06.882906+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:258:in `load_dependency' 2017-09-20T08:43:06.882907+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:379:in `block in require_or_load' 2017-09-20T08:43:06.882908+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:36:in `block in load_interlock' 2017-09-20T08:43:06.882908+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies/interlock.rb:12:in `block in loading' 2017-09-20T08:43:06.882909+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/concurrency/share_lock.rb:149:in `exclusive' 2017-09-20T08:43:06.882910+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies/interlock.rb:11:in `loading' 2017-09-20T08:43:06.882910+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:36:in `load_interlock' 2017-09-20T08:43:06.882911+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:357:in `require_or_load' 2017-09-20T08:43:06.882912+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:335:in `depend_on' 2017-09-20T08:43:06.882913+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.4/lib/active_support/dependencies.rb:251:in `require_dependency' 2017-09-20T08:43:06.882917+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:476:in `block (2 levels) in eager_load!' 2017-09-20T08:43:06.882919+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:475:in `each' 2017-09-20T08:43:06.882919+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:475:in `block in eager_load!' 2017-09-20T08:43:06.882920+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:473:in `each' 2017-09-20T08:43:06.882921+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:473:in `eager_load!' 2017-09-20T08:43:06.882922+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/engine.rb:354:in `eager_load!' 2017-09-20T08:43:06.882922+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/application/finisher.rb:67:in `each' 2017-09-20T08:43:06.882923+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/application/finisher.rb:67:in `block in <module:Finisher>' 2017-09-20T08:43:06.882924+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/initializable.rb:30:in `instance_exec' 2017-09-20T08:43:06.882924+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/initializable.rb:30:in `run' 2017-09-20T08:43:06.882925+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/initializable.rb:59:in `block in run_initializers' 2017-09-20T08:43:06.882926+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each' 2017-09-20T08:43:06.882927+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from' 2017-09-20T08:43:06.882927+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component' 2017-09-20T08:43:06.882928+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component' 2017-09-20T08:43:06.882929+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each' 2017-09-20T08:43:06.882929+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `call' 2017-09-20T08:43:06.882930+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component' 2017-09-20T08:43:06.882931+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each' 2017-09-20T08:43:06.882931+00:00 app[web.1]: /app/vendor/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each' 2017-09-20T08:43:06.882932+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/initializable.rb:58:in `run_initializers' 2017-09-20T08:43:06.882933+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/railties-5.1.4/lib/rails/application.rb:353:in `initialize!' 2017-09-20T08:43:06.882933+00:00 app[web.1]: /app/config/environment.rb:5:in `<top (required)>' 2017-09-20T08:43:06.882934+00:00 app[web.1]: config.ru:3:in `require_relative' 2017-09-20T08:43:06.882935+00:00 app[web.1]: config.ru:3:in `block in <main>' 2017-09-20T08:43:06.882935+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `instance_eval' 2017-09-20T08:43:06.882936+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `initialize' 2017-09-20T08:43:06.882937+00:00 app[web.1]: config.ru:in `new' 2017-09-20T08:43:06.882938+00:00 app[web.1]: config.ru:in `<main>' 2017-09-20T08:43:06.882939+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/rack-2.0.3/lib/rack/builder.rb:49:in `eval' 2017-09-20T08:43:06.882940+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/rack-2.0.3/lib/rack/builder.rb:49:in `new_from_string' 2017-09-20T08:43:06.882940+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/rack-2.0.3/lib/rack/builder.rb:40:in `parse_file' 2017-09-20T08:43:06.882941+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/configuration.rb:314:in `load_rackup' 2017-09-20T08:43:06.882942+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/configuration.rb:243:in `app' 2017-09-20T08:43:06.882942+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/runner.rb:138:in `load_and_bind' 2017-09-20T08:43:06.882943+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/single.rb:87:in `run' 2017-09-20T08:43:06.882944+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/launcher.rb:183:in `run' 2017-09-20T08:43:06.882945+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/lib/puma/cli.rb:77:in `run' 2017-09-20T08:43:06.882945+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/gems/puma-3.10.0/bin/puma:10:in `<top (required)>' 2017-09-20T08:43:06.882946+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/bin/puma:23:in `load' 2017-09-20T08:43:06.882947+00:00 app[web.1]: /app/vendor/bundle/ruby/2.3.0/bin/puma:23:in `<top (required)>' 2017-09-20T08:43:07.087698+00:00 heroku[web.1]: State changed from starting to crashed 2017-09-20T08:43:07.066935+00:00 heroku[web.1]: Process exited with status 1 2017-09-20T08:44:33.090373+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrouded-escarpment-49254.herokuapp.com request_id=1f54f52d-47da-4dba-8540-6d2db0065e29 fwd="85.95.188.63" dyno= connect= service= status=503 bytes= protocol=https 2017-09-20T08:44:33.835308+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrouded-escarpment-49254.herokuapp.com request_id=0283b085-1d25-44e3-8cdc-37b9ff78ab24 fwd="85.95.188.63" dyno= connect= service= status=503 bytes= protocol=https 2017-09-20T08:44:50.918925+00:00 app[api]: Starting process with command `bundle exec rake -T` by user flexaccess@hotmail.com 2017-09-20T08:44:54.143017+00:00 heroku[run.9336]: Awaiting client 2017-09-20T08:44:54.176007+00:00 heroku[run.9336]: Starting process with command `bundle exec rake -T` 2017-09-20T08:44:54.529997+00:00 heroku[run.9336]: State changed from starting to up 2017-09-20T08:45:00.154729+00:00 heroku[run.9336]: Process exited with status 0 2017-09-20T08:45:00.169298+00:00 heroku[run.9336]: State changed from up to complete 2017-09-20T08:45:19.430503+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrouded-escarpment-49254.herokuapp.com request_id=558dfeba-f2d1-419a-80ba-c9c4bf5b2b0a fwd="85.95.188.63" dyno= connect= service= status=503 bytes= protocol=https 2017-09-20T08:45:20.167192+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrouded-escarpment-49254.herokuapp.com request_id=504d156f-e3cd-4b19-8cd7-6ecbff1427ee fwd="85.95.188.63" dyno= connect= service= status=503 bytes= protocol=https