title: App not loading: "localhost didn’t send any data. ERR_EMPTY_RESPONSE"
body: <p>I just spent a week upgrading rails to 4.2.10, and upgraded a whole bunch of gems and such, and now that I've finally convinced rails to run without errors, my app won't actually load. </p>
  
  <pre><code>This page isn’t working
  localhost didn’t send any data.
  ERR_EMPTY_RESPONSE
  </code></pre>
  
  <p>I have no idea where to even start trying to debug this.</p>
  
  <p>The development.log file doesn't have any errors. The entire file says:</p>
  
  <pre><code>^[[1m^[[36mAppConfiguration Load (0.5ms)^[[0m  ^[[1mSELECT  `configurations`.* FROM `configurations` WHERE `configurations`.`type` IN ('AppConfiguration') AND `configurations`.`name` = 'Default configuration' LIMIT 1^[[0m
  Cache read: Spree::Config
  Dalli::Server#connect memcached:11211
  Cache fetch_hit: Spree::Config
  Cache read: Spree::Config
  Cache fetch_hit: Spree::Config
  Cache read: Spree::Config
  Cache fetch_hit: Spree::Config
  </code></pre>
  
  <p>And nothing new is printed when I hit the page.</p>
  
  <p><code>docker-compose logs -f abc</code> just says:</p>
  
  <pre><code>=&gt; Booting WEBrick
  =&gt; Rails 4.2.10 application starting in development on http://localhost:3000
  =&gt; Run `rails server -h` for more startup options
  =&gt; Ctrl-C to shutdown server
  
  [2018-08-17 14:48:01] INFO  WEBrick 1.3.1
  [2018-08-17 14:48:01] INFO  ruby 2.1.5 (2014-11-13) [x86_64-linux-gnu]
  [2018-08-17 14:48:01] INFO  WEBrick::HTTPServer#start: pid=18 port=3000
  </code></pre>
  
  <p>Would my Gemfile be useful? What else would helpful to share?</p>
  
  <p>It's not a local browser issue, because <code>curl</code> responds with <code>(52) Empty reply from server</code>, as well.</p>
  
  <p>In Firefox: <code>The connection to the server was reset while the page was loading.</code></p>
  
  <p>ETA: Solved by adding <code>-b 0.0.0.0</code> at the end of <code>bundle exec rails server</code></p>