title: Strange behavior in Rails 4.2.0.beta2 - Is this a bug?
body: <h1>Get a 500 error on <strong>every other</strong> window reload.</h1>
  <p><code>assets/application-CACHE-.js</code> not found. No Idea what is causing it. Development environment. Using Unicorn as my webserver. Anyone know what this is?</p>
  <pre><code>17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /blog HTTP/1.1&quot; 200 - 0.2885
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /about-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0110
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /blog-14053fca722628f43031ae06cb18c52c.css?body=1 HTTP/1.1&quot; 304 - 0.0110
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /contact-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0112
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /layouts/partials/footer-71929e4ed77e723296d6a937e6469653.css?body=1 HTTP/1.1&quot; 304 - 0.0116
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /portfolio-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0133
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /layouts/partials/navigation-1d28f98b6c63feaf0bd6b06fb5873475.css?body=1 HTTP/1.1&quot; 304 - 0.0136
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /resources-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0130
  17:07:13 web.1  | Rack::Lint::LintError: Content-Type header found in 304 response, not allowed
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:20:in `assert'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:651:in `block in check_content_type'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:647:in `each'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:647:in `check_content_type'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:58:in `_call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:37:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/showexceptions.rb:24:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/commonlogger.rb:33:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/chunked.rb:54:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/content_length.rb:15:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:576:in `process_client'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:670:in `worker_loop'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:525:in `spawn_missing_workers'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:140:in `start'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/bin/unicorn:126:in `&lt;top (required)&gt;'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/unicorn:23:in `load'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/unicorn:23:in `&lt;main&gt;'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `eval'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `&lt;main&gt;'
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /resume-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0139
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /welcome-64845c436e75ac587deec98177291d4e.css?body=1 HTTP/1.1&quot; 304 - 0.0138
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /jquery-6a50177757f6c64493882fb7aae952c3.js?body=1 HTTP/1.1&quot; 304 - 0.0148
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/affix-04c58ad484d0bdbdf9514b7d09505d25.js?body=1 HTTP/1.1&quot; 304 - 0.0141
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET %2Fassets%2Fapplication-2e47777fcdd4d7b3353ccfc1718b4f0c.css?body=1 HTTP/1.1&quot; 500 68784 0.0266
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/button-c9d4d44342d7be7abeb23fb0edbe00b7.js?body=1 HTTP/1.1&quot; 304 - 0.0219
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/carousel-b0f1e7b56803d98d500f5ccc15d550e3.js?body=1 HTTP/1.1&quot; 304 - 0.0150
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/alert-8186e091f2fa7c9423e9cadae6ce4de4.js?body=1 HTTP/1.1&quot; 304 - 0.0258
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/collapse-417aacb8b3257798b481ed397b421b7c.js?body=1 HTTP/1.1&quot; 304 - 0.0158
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/tab-dec75af9b2ffeed03dc43eabdb771d48.js?body=1 HTTP/1.1&quot; 304 - 0.0123
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/dropdown-f5a24e96d563b9a6d252c1c07a6ecc6b.js?body=1 HTTP/1.1&quot; 304 - 0.0142
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/modal-82015eda5031618c5aba3ebf9fc2cf4b.js?body=1 HTTP/1.1&quot; 304 - 0.0123
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/transition-3005c626234d995c29e4bcbd07b3ac0c.js?body=1 HTTP/1.1&quot; 304 - 0.0138
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/scrollspy-f421d662af4612a610656bfeee3407d9.js?body=1 HTTP/1.1&quot; 304 - 0.0140
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap-sprockets-99470846ba99b7073a929a36d4cee32a.js?body=1 HTTP/1.1&quot; 304 - 0.0139
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/tooltip-5e9e765caafcbcb1672a3e72ef7f4a3a.js?body=1 HTTP/1.1&quot; 304 - 0.0158
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /bootstrap/popover-df8ed104d2525bbc4b4dad060e68cf99.js?body=1 HTTP/1.1&quot; 304 - 0.0211
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /jquery_ujs-03cb26c4b41579fc5e95ea8f47ac5e18.js?body=1 HTTP/1.1&quot; 304 - 0.0148
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /turbolinks-ebcce04d6463d2d77b51c18291df6925.js?body=1 HTTP/1.1&quot; 304 - 0.0162
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /about-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0140
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /blog-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0145
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /contact-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0164
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /portfolio-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0178
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /resources-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0131
  17:07:13 web.1  | Rack::Lint::LintError: Content-Type header found in 304 response, not allowed
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:20:in `assert'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:651:in `block in check_content_type'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:647:in `each'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:647:in `check_content_type'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:58:in `_call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/lint.rb:37:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/showexceptions.rb:24:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/commonlogger.rb:33:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/chunked.rb:54:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/rack-1.6.0.beta/lib/rack/content_length.rb:15:in `call'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:576:in `process_client'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:670:in `worker_loop'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:525:in `spawn_missing_workers'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/lib/unicorn/http_server.rb:140:in `start'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/gems/unicorn-4.8.3/bin/unicorn:126:in `&lt;top (required)&gt;'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/unicorn:23:in `load'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/unicorn:23:in `&lt;main&gt;'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `eval'
  17:07:13 web.1  |   /Users/fab/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `&lt;main&gt;'
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /resume-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0131
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET /welcome-32740fa4bc301ff5ef2eca5d8d82335a.js?body=1 HTTP/1.1&quot; 304 - 0.0147
  17:07:13 web.1  | 127.0.0.1 - - [15/Oct/2014:17:07:13 -0400] &quot;GET %2Fassets%2Fapplication-c17db73b14421ee3a4d7e97bd3a6041c.js?body=1 HTTP/1.1&quot; 500 68757 0.0217
  </code></pre>
  <p>Every <strong>other page reload</strong> I get 500 internal error assets not found:</p>
  <pre><code>GET http://localhost:5000/assets/application-ddb2488b062b582487dc9a71475f69b3.css?body=1 
  GET http://localhost:5000/assets/application-89761eef2e06fafdfbe675623cff99d7.js?body=1  
  </code></pre>