Nasty bug with binary files, Rails and erb.rb – how to fix it

OK, so I happily hack away on my  Rails application on a Debian box with Ruby 1.8.7 and Rails 2.1.0, and then deploy to a Fedora 8 server with Ruby 1.8.6 and Rails 2.2.2. All of a sudden a particular release causes Passenger to spit an error page on application startup. The key error was:

undefined method empty?' for nil:NilClass

Now I'm combing all over my code to find where I'm using "empty?" but I'm sure it's somewhere that gets run on application startup, otherwise it wouldn't show up when Passenger tries to start the application. But I find nothing and I'm about to shoot myself.

Following the trace I end up hacking Ruby's erb.rb file, as there appear to be some bugs in this; indeed, this one from 1.8.6 is different from what I have in 1.8.7, so the app runs fine here. I try to fix instances where empty? might get called on a nil object, but after fixing 3 of these the app stops responding altogether. Hmm, so something, somewhere, depends on erb.rb's buggy behavior. Best to leave it alone.

HOWEVER, on the deployment server, running with script/server works fine; it's only when using Passenger that things blow up.

Finally I find this thread that points me in the right direction:

One of the users dropped some
JPEG files into the /app/views/static directory, and that seems to be
jamming up the works with 2.2.2.

Indeed, as part of my last set of revisions, I'd left several samples of static content I was converting into dynamically generated pages; sure enough, they included JPGs and whatnot. Just to be safe, I decided to move the entire directory into public to avoid any problems.

Now the app runs just peachy and I only wasted 2 hours chasing down this bug. Thanks to the guys at Nabble!

Eventually it all boils down to this Rails bug reported at Lighthouse. So hopefully it'll be fixed soon. In the meanwhile, keep binary files out of your views subtree.

I'm attaching the entire Passenger error page, in case it's useful to anyone. Mainly so that Google can find it faster for other people with this problem.

Ruby on Rails application could not be started

These are the possible causes:

  • There may be a syntax error in the application's code. Please check for such errors and fix them.
  • A required library may not installed. Please install all libraries that this application requires.
  • The application may not be properly configured. Please check whether all configuration files are written correctly, fix any incorrect configurations, and restart this application.
  • A service that the application relies on (such as the database server or the Ferret search engine server) may not have been started. Please start that service.

Further information about the error may have been written to the application's log file. Please check it in order to analyse the problem.

Error message:
undefined method empty?’ for nil:NilClass
Exception class:
Application root:
# File Line Location
0 /usr/lib/ruby/1.8/erb.rb 478 in scan'
1 /usr/lib/ruby/1.8/erb.rb 524 in compile’
2 /usr/lib/ruby/1.8/erb.rb 691 in initialize'
3 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/template_handlers/erb.rb 51 in new’
4 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/template_handlers/erb.rb 51 in compile'
5 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/template_handler.rb 11 in call’
6 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/renderable.rb 21 in _unmemoized_compiled_source'
7 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 57 in compiled_source’
8 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 25 in __send__'
9 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 25 in memoize_all’
10 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 22 in each'
11 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 22 in memoize_all’
12 /usr/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/memoizable.rb 17 in freeze'
13 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 88 in reload!’
14 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 102 in templates_in_path'
15 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 100 in each’
16 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 100 in templates_in_path'
17 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 86 in reload!’
18 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 78 in load'
19 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 109 in load’
20 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 109 in each'
21 /usr/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_view/paths.rb 109 in load’
22 /usr/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb 357 in load_view_paths'
23 /usr/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb 182 in process’
24 /usr/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb 112 in send'
25 /usr/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb 112 in run’
26 ./config/environment.rb 13
27 /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb 31 in gem_original_require'
28 /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb 31 in require’
29 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/railz/application_spawner.rb 254 in preload_application'
30 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/railz/application_spawner.rb 214 in initialize_server’
31 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/utils.rb 179 in report_app_init_status'
32 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/railz/application_spawner.rb 203 in initialize_server’
33 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 166 in start_synchronously'
34 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 135 in start’
35 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 112 in fork'
36 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 112 in start’
37 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/railz/application_spawner.rb 179 in start'
38 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/spawn_manager.rb 222 in spawn_rails_application’
39 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/spawn_manager.rb 217 in synchronize'
40 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/spawn_manager.rb 217 in spawn_rails_application’
41 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/spawn_manager.rb 126 in spawn_application'
42 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/spawn_manager.rb 251 in handle_spawn_application’
43 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 317 in __send__'
44 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 317 in main_loop’
45 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/lib/passenger/abstract_server.rb 168 in `start_synchronously’
46 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.6/bin/passenger-spawn-server 46