title: First Heroku Push of Application to Heroku leads to Application Error
body: <p>I am relatively new to Heroku and Rails. I have pushed a small "app" to Heroku before which worked fine. </p>
  
  <p>Now I have developed a bit of a larger application on my desktop pc, which runs fine using my rails server as localhost.</p>
  
  <p>When I try migrating it to Heroku I get the following message:</p>
  
  <pre><code>   Application Error
     =================
  
     An error occurred in the application and your page could not be served. Please try again   in a few moments.
  
     If you are the application owner, check your logs for details.
  </code></pre>
  
  <p>I started looking at the log files, but they don't really tell me anything. Can someone please give me a hint on how to interpret them. I think the last to logfile lines are the ones that crash the application:</p>
  
  <pre><code>2013-08-12T17:54:56.944875+00:00 app[web.1]: /app/vendor/bundle/ruby/2.0.0/gems/bundler-1.3.2/lib/bundler/rubygems_integration.rb:224:in `block in replace_gem': can't activate bcrypt-ruby (~&gt; 3.0.0), already activated bcrypt-ruby-3.1.1. Make sure all dependencies are added to Gemfile. (Gem::LoadError)
  </code></pre>
  
  <p><strong>EDIT: I've now added the complete 'heroku logs' prompt output. Any suggestions on what to look for. I'm very unfamiliar with the log output, don't really know where to start.</strong></p>
  
  <p><strong>EDIT 2: Thanks for all the help so far! I've got the app working now. The following was the problem</strong></p>
  
  <p>In my gem file I had ByCrypt linked in like this:</p>
  
  <pre><code>gem 'bcrypt-ruby', :require =&gt; 'bcrypt'
  </code></pre>
  
  <p>Since the Heroku logs said something about </p>
  
  <pre><code>can't activate bcrypt-ruby (~&gt; 3.0.0), already activated bcrypt-ruby-3.1.1.
  </code></pre>
  
  <p>I changed my Gemfile to</p>
  
  <pre><code>gem 'bcrypt-ruby', '~&gt; 3.0.0'
  </code></pre>
  
  <p>This helped! The app is now running on heroku. But I think I now have a problem with the methods using bcrypt... but I will have to investigate this seperately. Thanks for the help!</p>