title: Passenger: internal server error
body: <p>I installed Apache, Passenger and Sinatra and deployed an app. It gives error when trying to access:</p>
  
  <pre><code>An error occurred while starting up the preloader: it did not write a startup response in time.
  
  Application root
      /var/www/html/test
  Environment (value of RAILS_ENV, RACK_ENV, WSGI_ENV and PASSENGER_ENV)
      production
  Ruby interpreter command
  
      /usr/local/bin/ruby
  
  User and groups
  
      Unknown
  
  Environment variables
  
      Unknown
  
  Ulimits
  
      Unknown
  </code></pre>
  
  <p>How can I solve it?</p>
  
  <hr>
  
  <p><strong>Edit</strong></p>
  
  <p>In the application log, I found this line of error:</p>
  
  <pre><code>!&gt; Ready
  !&gt; socket: unix:/tmp/passenger.1.0.14019/generation-0/backends/preloader.14049
  !&gt;
  </code></pre>
  
  <p>Gem list:</p>
  
  <pre><code>bigdecimal (1.2.0)
  builder (3.2.0)
  bundler (1.3.1)
  daemon_controller (1.1.1)
  fastthread (1.0.7)
  io-console (0.4.2)
  json (1.7.7)
  minitest (4.3.2)
  passenger (4.0.0.rc4)
  psych (2.0.0)
  rack (1.5.2)
  rack-protection (1.4.0)
  rake (0.9.6)
  rdoc (4.0.0)
  sequel (3.45.0)
  sinatra (1.3.5)
  test-unit (2.0.0.0)
  tilt (1.3.4)
  </code></pre>
  
  <p>System version:</p>
  
  <pre><code>Ruby 2.0
  Apache 2.2
  Amazon EC2 Instance
  </code></pre>
  
  <p>The app was running fine with Ruby 1.9 and Passenger 3.0. I just upgraded to 2.0, and Passenger 3.0 does not even compile correctly. They suggested me to use Passenger Pre 4.0, and it compiled fine, but does not run the app...</p>