Rails 4: Push rejected, failed to compile Ruby app - ruby-on-rails

Question

I am working on a Rails 4.
As a best practice recommended in Michael Hartl's Rails Tutorial, I try to deploy early and often to avoid compounded problems as development progresses.
Everything was working just fine until recently: I was running git push heroku master and the app was working in the same way, both locally and on Heroku.
However, now, when I try to push my code to Heroku, I get the following error:
Counting objects: 26, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (25/25), done.
Writing objects: 100% (26/26), 3.07 KiB | 0 bytes/s, done.
Total 26 (delta 14), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Ruby app detected
remote: -----> Compiling Ruby/Rails
remote: -----> Using Ruby version: ruby-2.0.0
remote: -----> Installing dependencies using 1.9.7
remote: Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
remote: Rubygems 2.0.14 is not threadsafe, so your gems must be installed one at a time. Upgrade to Rubygems 2.1.0 or higher to enable parallel gem installation.
remote: Using rake 10.4.2
remote: Using i18n 0.7.0
remote: Using json 1.8.3
remote: Using minitest 5.8.0
remote: Using thread_safe 0.3.5
remote: Using tzinfo 1.2.2
remote: Using activesupport 4.2.2
remote: Using builder 3.2.2
remote: Using erubis 2.7.0
remote: Using mini_portile 0.6.2
remote: Using nokogiri 1.6.6.2
remote: Using rails-deprecated_sanitizer 1.0.3
remote: Using rails-dom-testing 1.0.7
remote: Using loofah 2.0.3
remote: Using rails-html-sanitizer 1.0.2
remote: Using actionview 4.2.2
remote: Using rack 1.6.4
remote: Using rack-test 0.6.3
remote: Using actionpack 4.2.2
remote: Using globalid 0.3.6
remote: Using activejob 4.2.2
remote: Using mime-types 2.6.1
remote: Using mail 2.6.3
remote: Using actionmailer 4.2.2
remote: Using activemodel 4.2.2
remote: Using arel 6.0.3
remote: Using activerecord 4.2.2
remote: Using execjs 2.6.0
remote: Using autoprefixer-rails 5.2.1.2
remote: Using bcrypt 3.1.10
remote: Using sass 3.4.18
remote: Using bootstrap-sass 3.3.5.1
remote: Using coffee-script-source 1.9.1.1
remote: Using coffee-script 2.4.1
remote: Using thor 0.19.1
remote: Using railties 4.2.2
remote: Using coffee-rails 4.1.0
remote: Using orm_adapter 0.5.0
remote: Using responders 2.1.0
remote: Using warden 1.2.3
remote: Using devise 3.5.2
remote: Using multi_json 1.11.2
remote: Using jbuilder 2.3.1
remote: Using jquery-rails 4.0.4
remote: Using turbolinks 2.5.3
remote: Using jquery-turbolinks 2.1.0
remote: Using pg 0.18.2
remote: Using puma 2.13.4
remote: Using bundler 1.9.7
remote: Using sprockets 3.3.3
remote: Using sprockets-rails 2.3.2
remote: Using rails 4.2.2
remote: Using rails_serve_static_assets 0.0.4
remote: Using rails_stdout_logging 0.0.4
remote: Using rails_12factor 0.0.3
remote: Using rdoc 4.2.0
remote: Using tilt 1.4.1
remote: Using sass-rails 5.0.3
remote: Using sdoc 0.4.1
remote: Using uglifier 2.7.1
remote: Bundle complete! 22 Gemfile dependencies, 60 gems now installed.
remote: Gems in the groups development and test were not installed.
remote: Bundled gems are installed into ./vendor/bundle.
remote: Bundle completed (0.56s)
remote: Cleaning up the bundler cache.
remote: -----> Preparing app for Rails asset pipeline
remote: Running: rake assets:precompile
remote: rake aborted!
remote: SyntaxError: /tmp/build_c8c1797d62ce933566e19803262e7a1d/config/environments/production.rb:95: syntax error, unexpected keyword_end, expecting '}'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `block in require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:240:in `load_dependency'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/engine.rb:598:in `block (2 levels) in <class:Engine>'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/engine.rb:597:in `each'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/engine.rb:597:in `block in <class:Engine>'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:30:in `instance_exec'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:30:in `run'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:55:in `block in run_initializers'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:44:in `each'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:44:in `tsort_each_child'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/initializable.rb:54:in `run_initializers'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/application.rb:352:in `initialize!'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/config/environment.rb:5:in `<top (required)>'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `block in require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:240:in `load_dependency'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/activesupport-4.2.2/lib/active_support/dependencies.rb:274:in `require'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/application.rb:328:in `require_environment!'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/railties-4.2.2/lib/rails/application.rb:457:in `block in run_tasks_blocks'
remote: /tmp/build_c8c1797d62ce933566e19803262e7a1d/vendor/bundle/ruby/2.0.0/gems/sprockets-rails-2.3.2/lib/sprockets/rails/task.rb:64:in `block (2 levels) in define'
remote: Tasks: TOP => environment
remote: (See full trace by running task with --trace)
remote: !
remote: ! Precompiling assets failed.
remote: !
remote:
remote: ! Push rejected, failed to compile Ruby app
remote:
remote: Verifying deploy....
remote:
remote: ! Push rejected to calendy.
remote:
To https://git.heroku.com/calendy.git
! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/calendy.git'
I am not quite sure, but I believe this error started happening after I ran heroku run rake db:reset as I wanted to reset my Heroku databse.
Here are the solutions I tried before posting this question:
Run git pull heroku master and then run git push heroku master.
Run bundle install in case the issue was caused by the Gemfile.
Login to Heroku, link my GitHub account to Heroku and deploy manually.
None of the above worked.
There are two things here that I can't seem to understand:
What is going wrong and how I can fix it?
Why things stopped working in the first place?

Answer 1

Ok, I just understood my mistake.
There was a syntax error in my production.rb file, as mentioned in the terminal code I shared in the question:
remote: SyntaxError: /tmp/build_c8c1797d62ce933566e19803262e7a1d/config/environments/production.rb:95: syntax error, unexpected keyword_end, expecting '}'
I just had to:
fix this syntax error in the production.rb file — i.e. add the missing } to my code
run git add .
run git commit -m "Fix production.rb syntax error"
run git push origin master
and then git push heroku master started working again like a charm.