title: "rails generate scaffold" error on "_from.erb" (jbuilder issue?)
body: <p>I'm relatively new to Ruby and Rails, been teaching myself in free time. I recently added a few gems to my gemfile, and now my scaffold is giving me errors--couldn't find another answer on StackOverflow that addressed my issue (apologies in advance if my search prowess isn't up to par).</p>
  <p>Gemfile:</p>
  <pre><code>source 'https://rubygems.org'
  git_source(:github) { |repo| &quot;https://github.com/#{repo}.git&quot; }
  
  ruby '2.5.1'
  
  # Set up local .env file, require immediately
  gem 'dotenv-rails', :require =&gt; 'dotenv/rails-now'
  
  # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
  gem 'rails', '~&gt; 5.2.1'
  
  # Use postgresql as the database for Active Record
  gem 'pg'
  # Use Puma as the app server
  gem 'puma', '~&gt; 3.11'
  # Use SCSS for stylesheets
  gem 'sass-rails', '~&gt; 5.0'
  # Use Uglifier as compressor for JavaScript assets
  gem 'uglifier', '&gt;= 1.3.0'
  # See https://github.com/rails/execjs#readme for more supported runtimes
  gem 'duktape'
  # Use CoffeeScript for .coffee assets and views
  gem 'coffee-rails', '~&gt; 4.2'
  # Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
  gem 'turbolinks', '~&gt; 5'
  # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
  gem 'jbuilder', '~&gt; 2.5'
  # Use Redis adapter to run Action Cable in production
  # gem 'redis', '~&gt; 4.0'
  # Use ActiveModel has_secure_password
  gem 'bcrypt', '~&gt; 3.1.7'
  
  # Use ActiveStorage variant
  # gem 'mini_magick', '~&gt; 4.8'
  
  # Use Capistrano for deployment
  # gem 'capistrano-rails', group: :development
  
  # Reduces boot times through caching; required in config/boot.rb
  gem 'bootsnap', '&gt;= 1.1.0', require: false
  
  group :development, :test do
    # Call 'byebug' anywhere in the code to stop execution and get a debugger console
    gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  end
  
  group :development do
    # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
    gem 'web-console', '&gt;= 3.3.0'
    # Mailcatcher for local mail debugging
    gem 'mailcatcher'
  end
  
  group :test do
    # Adds support for Capybara system testing and selenium driver
    gem 'capybara', '&gt;= 2.15', '&lt; 4.0'
    gem 'selenium-webdriver'
    # Easy installation and use of chromedriver to run system tests with Chrome
    gem 'chromedriver-helper'
  end
  
  # group :development, :test do
  #   gem 'foreman'
  # end
  
  # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
  gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
  
  #Add Sprockets for installing gems
  gem 'sprockets-rails', '&gt;= 2.3.2', :require =&gt; 'sprockets/railtie'
  
  #Add Bootstrap
  gem 'bootstrap', '&gt;= 4.1.3'
  
  #Add JQuery (for Bootstrap)
  gem 'jquery-rails', '~&gt; 4.3.1'
  
  #Add Chart.js for analytics
  gem 'chart-js-rails', '~&gt; 0.1.6' 
  
  #Add Devise for Authorization and Authentication
  gem 'devise', '~&gt; 4.4.3'
  
  #Add Font Awesome Icons
  gem 'font-awesome-sass', '~&gt; 5.2.0'
  
  #Mini-Magick for Image Processing (のし Generator)
  gem 'mini_magick'
  
  #Auto-upload setup for AWS S3
  gem 'carrierwave'
  gem 'carrierwave-google-storage'
  
  # Easy Categories for Manual Articles
  gem 'ancestry'
  
  # CKEditor WYSIWYG text editor
  gem 'simple_form'
  gem 'ckeditor', github: 'galetahub/ckeditor'
  
  # Sendgrid for confirmations, etc.
  gem 'sendgrid-ruby'
  </code></pre>
  <p>And here's the error when I try to generate the scaffold:</p>
  <pre><code>rails generate scaffold Market namae:string address:string phone:string repphone:string fax:string cost:decimal excost:decimal history:string
        invoke  active_record
     identical    db/migrate/20181029224847_create_markets.rb
     identical    app/models/market.rb
        invoke    test_unit
     identical      test/models/market_test.rb
     identical      test/fixtures/markets.yml
        invoke  resource_route
         route    resources :markets
        invoke  scaffold_controller
     identical    app/controllers/markets_controller.rb
        invoke    erb
         exist      app/views/markets
      conflict      app/views/markets/index.html.erb
      Overwrite /home/mudl/kanri/Dropbox/funabiki-online-h/app/views/markets/index.html.erb? (enter &quot;h&quot; for help) [Ynaqdh] n
          skip      app/views/markets/index.html.erb
     identical      app/views/markets/edit.html.erb
     identical      app/views/markets/show.html.erb
      conflict      app/views/markets/new.html.erb
      Overwrite /home/mudl/kanri/Dropbox/funabiki-online-h/app/views/markets/new.html.erb? (enter &quot;h&quot; for help) [Ynaqdh] n
          skip      app/views/markets/new.html.erb
  Traceback (most recent call last):
      71: from bin/rails:4:in `&lt;main&gt;'
      70: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activesupport-5.2.1/lib/active_support/dependencies.rb:287:in `require'
      69: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activesupport-5.2.1/lib/active_support/dependencies.rb:253:in `load_dependency'
      68: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activesupport-5.2.1/lib/active_support/dependencies.rb:287:in `block in require'
      67: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/bootsnap-1.3.2/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
      66: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/bootsnap-1.3.2/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
      65: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/bootsnap-1.3.2/lib/bootsnap/load_path_cache/loaded_features_index.rb:65:in `register'
      64: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/bootsnap-1.3.2/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
      63: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/bootsnap-1.3.2/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
      62: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/commands.rb:18:in `&lt;main&gt;'
      61: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/command.rb:46:in `invoke'
      60: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/command/base.rb:65:in `perform'
      59: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor.rb:369:in `dispatch'
      58: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
      57: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
      56: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/commands/generate/generate_command.rb:26:in `perform'
      55: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators.rb:276:in `invoke'
      54: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/base.rb:444:in `start'
      53: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:232:in `dispatch'
      52: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `invoke_all'
      51: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `map'
      50: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `each'
      49: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `block in invoke_all'
      48: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
      47: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
      46: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:133:in `_invoke_from_option_scaffold_controller'
      45: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:266:in `_invoke_for_class_method'
      44: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/shell.rb:68:in `with_padding'
      43: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:277:in `block in _invoke_for_class_method'
      42: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:115:in `invoke'
      41: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:232:in `dispatch'
      40: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `invoke_all'
      39: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `map'
      38: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `each'
      37: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `block in invoke_all'
      36: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
      35: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
      34: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:133:in `_invoke_from_option_template_engine'
      33: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:266:in `_invoke_for_class_method'
      32: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/shell.rb:68:in `with_padding'
      31: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:274:in `block in _invoke_for_class_method'
      30: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:274:in `instance_exec'
      29: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/rails/scaffold_controller/scaffold_controller_generator.rb:26:in `block in &lt;class:ScaffoldControllerGenerator&gt;'
      28: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:115:in `invoke'
      27: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/group.rb:232:in `dispatch'
      26: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `invoke_all'
      25: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `map'
      24: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `each'
      23: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:133:in `block in invoke_all'
      22: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
      21: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
      20: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/erb/scaffold/scaffold_generator.rb:18:in `copy_view_files'
      19: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/erb/scaffold/scaffold_generator.rb:18:in `each'
      18: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/erb/scaffold/scaffold_generator.rb:19:in `block in copy_view_files'
      17: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/erb/scaffold/scaffold_generator.rb:19:in `each'
      16: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/erb/scaffold/scaffold_generator.rb:21:in `block (2 levels) in copy_view_files'
      15: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/named_base.rb:24:in `template'
      14: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/named_base.rb:49:in `inside_template'
      13: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/generators/named_base.rb:25:in `block in template'
      12: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/file_manipulation.rb:115:in `template'
      11: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/create_file.rb:25:in `create_file'
      10: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions.rb:95:in `action'
       9: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/create_file.rb:60:in `invoke!'
       8: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/empty_directory.rb:113:in `invoke_with_conflict_check'
       7: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/create_file.rb:72:in `on_conflict_behavior'
       6: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/create_file.rb:46:in `identical?'
       5: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/create_file.rb:53:in `render'
       4: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.19.4/lib/thor/actions/file_manipulation.rb:116:in `block in template'
       3: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/2.5.0/erb.rb:876:in `result'
       2: from /home/mudl/.rbenv/versions/2.5.1/lib/ruby/2.5.0/erb.rb:876:in `eval'
       1: from (erb):2:in `template'
  (erb):2:in `concat': can't modify frozen String (FrozenError)
  </code></pre>
  <p>As you can see it seems to be having an issue when it gets to the &quot;_form.html&quot; part of the scaffold generation.</p>
  <p>I checked to make sure there were no strange permissions on files. I suspect it has something to do with Foreman (which is a Heroku thing), or maybe dotenv (which is necessary for local development stuff, so I can store secrets). I found some posts elsewhere about previous beta versions of rails 5.1 have issues with Thor, but I don't even know what Thor does (it is some dependency) and they said that that bug was fixed on subsequent releases (e.g. I'm using 5.2 anyway).</p>
  <p>My other theory is that it's related to Jbuilder and json stuff, which I'm also new to, and don't even know where to begin to tackle.</p>
  <p>Any ideas? In the meantime I'm going to work without scaffolding.</p>
  <p>Anyway, thank you for your time!</p>
  <p>Thank you for your time!</p>
  <hr>
  <p>Update!</p>
  <p>Well, I solved the problem on my own, and just wanted to report back. So, I forgot I had had trouble installing Nokogiri as well. Whenever I ran &quot;bundle update&quot; I was getting an error that said I needed to make sure the latest version of Nokogiri was installed correctly before continuing. I ignored this, because I couldn't figure out out. This was solved by simply following the instructions at <a href="http://www.nokogiri.org/tutorials/installing_nokogiri.html" rel="nofollow noreferrer">nokogiri.org</a> and installing the necessary libraries:</p>
  <blockquote>
  <p>sudo apt-get install build-essential patch ruby-dev zlib1g-dev
  liblzma-dev</p>
  <p>gem install nokogiri</p>
  </blockquote>
  <p>After I did this I thought to myself &quot;Uh, duh, this is probably the solution to the scaffolding issue.&quot; Indeed it was.</p>