Paperclip - undefined method `match' for nil:NilClass - ruby-on-rails

Question

I'm new to rails, and ruby. I'm creating a simple application where I can upload a photo. I have the paperclip gem installed and I'm trying to configure it within my model to specify a thumbnail size like so:
has_attached_file :photo,
:styles => {:thumb => '120x120>', :large => '640x480>' },
:default_style => :thumb,
:url => "/system/photos/:basename.:extension",
:path => ":rails_root/public/system/photos/:basename.:extension"
However, I keep receiving the error:
undefined method `match' for nil:NilClass
When I remove the :styles parameter, everything works as expected.
Can anybody shed some light and point me in the right direction?
Thanks
EDIT:
Stack trace is as follows:
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/content_type_detector.rb:60:in `type_from_file_command'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/content_type_detector.rb:16:in `detect'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/io_adapters/file_adapter.rb:14:in `cache_current_values'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/io_adapters/file_adapter.rb:5:in `initialize'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/io_adapters/registry.rb:29:in `new'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/io_adapters/registry.rb:29:in `for'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:412:in `post_process_style'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:402:in `block in post_process_styles'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:401:in `each'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:401:in `post_process_styles'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:394:in `block (2 levels) in post_process'
activesupport (3.2.7) lib/active_support/callbacks.rb:403:in `_run__792123923__photo_post_process__530674861__callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.7) lib/active_support/callbacks.rb:385:in `_run_photo_post_process_callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/callbacks.rb:26:in `run_paperclip_callbacks'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:393:in `block in post_process'
activesupport (3.2.7) lib/active_support/callbacks.rb:403:in `_run__792123923__post_process__530674861__callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.7) lib/active_support/callbacks.rb:385:in `_run_post_process_callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/callbacks.rb:26:in `run_paperclip_callbacks'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:392:in `post_process'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip/attachment.rb:107:in `assign'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/bundler/gems/paperclip-70f0f1fea030/lib/paperclip.rb:196:in `block in has_attached_file'
activerecord (3.2.7) lib/active_record/attribute_assignment.rb:85:in `block in assign_attributes'
activerecord (3.2.7) lib/active_record/attribute_assignment.rb:78:in `each'
activerecord (3.2.7) lib/active_record/attribute_assignment.rb:78:in `assign_attributes'
activerecord (3.2.7) lib/active_record/base.rb:498:in `initialize'
activerecord (3.2.7) lib/active_record/persistence.rb:44:in `new'
activerecord (3.2.7) lib/active_record/persistence.rb:44:in `create'
app/controllers/photography_controller.rb:23:in `create'
actionpack (3.2.7) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.7) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.7) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.7) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.7) lib/active_support/callbacks.rb:414:in `_run__403597772__process_action__67609296__callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.7) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.7) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.7) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.7) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.7) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.7) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.7) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.7) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.7) lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
activerecord (3.2.7) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.7) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.7) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.7) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.7) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.7) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.7) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.7) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.7) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.4) lib/journey/router.rb:68:in `block in call'
journey (1.0.4) lib/journey/router.rb:56:in `each'
journey (1.0.4) lib/journey/router.rb:56:in `call'
actionpack (3.2.7) lib/action_dispatch/routing/route_set.rb:600:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.1) lib/rack/etag.rb:23:in `call'
rack (1.4.1) lib/rack/conditionalget.rb:35:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/cookies.rb:338:in `call'
activerecord (3.2.7) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.7) lib/active_record/connection_adapters/abstract/connection_pool.rb:473:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.7) lib/active_support/callbacks.rb:405:in `_run__122749671__call__530674861__callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.7) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.7) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.7) lib/rails/rack/logger.rb:26:in `call_app'
railties (3.2.7) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.7) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.7) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.7) lib/rails/engine.rb:479:in `call'
railties (3.2.7) lib/rails/application.rb:220:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.7) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
PhotographyController:
def create
#photo = Photo.create(params[:photo])
end
And finally, my form partial may be of some help:
<%= form_for #photo, :url => { :controller => 'photography', :action => 'create'}, :html => { :multipart => true } do |f| %>
<% if #photo.errors.any? %>
<div id="errorExplanation">
<h2><%= pluralize(#photo.errors.count, "error") %> prohibited
this photo from being saved:</h2>
<ul>
<% #photo.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :title %><br />
<%= f.text_field :title %>
</div>
<div class="field">
<%= f.label :description %><br />
<%= f.text_area :description %>
</div>
<%= f.file_field :photo %>
<div class="actions">
<%= f.submit ('Upload Photo') %>
</div>
<% end %>
Thanks again.

Answer 1

I've ran into this error, and other similar ones as well, using paperclip. But I run my development environment on windows, and the latest version of paperclip uses the `file' command, which windows doesn't seem to like so much.
Hopefully this will be fixed soon, but for now I sidestepped the issue by using the last version of paperclip that works, namely 3.0.4.
If you're running on windows as well, just add this to your Gemfile:
gem 'paperclip', '3.0.4'
P.S. It might be worthwhile to try using 3.0.4 on development, and the latest version on production.

Answer 2

As the accepted answer suggests, this error can happen when Paperclip is unhappy for a variety of reasons.
In my case, I was upgrading from 4.1.1 to 6.1.0 and encountered this error.
The update required that I use the aws-sdk-s3 gem.
I resolved the error by setting s3_region in the paperclip config which is required when using aws-sdk-s3.