wrong number of arguments (0 for 1) upon adding an erb file for controller action

I am facing a really weird issue and unfortunately, rails doesn't provide any useful stack traces for debugging. I have a standard controller, posts_controller. In the routes, I have defined resources :posts.

I have implemented a basic index action. If I go to .../posts, the output is "Template is missing" which is expected because I haven't created the index.html.erb file in the views/posts directory.

HOWEVER, after I create a blank index.html.erb file in that directory, I get "wrong number of arguments (0 for 1)".

There is NO application trace.

The framework trace is:

actionpack (3.0.3) lib/action_controller/metal/rendering.rb:18:in `content_type'
actionpack (3.0.3) lib/action_controller/metal/rendering.rb:18:in `render'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:40:in `render'
activesupport (3.0.3) lib/active_support/core_ext/benchmark.rb:5:in `ms'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/benchmark.rb:308:in `realtime'
activesupport (3.0.3) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:40:in `render'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:78:in `cleanup_view_runtime'
activerecord (3.0.3) lib/active_record/railties/controller_runtime.rb:15:in `cleanup_view_runtime'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.0.3) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.0.3) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:151:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rendering.rb:11:in `process_action'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:18:in `process_action'
activesupport (3.0.3) lib/active_support/callbacks.rb:450:in `_run__84203013__process_action__199225275__callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `send'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `_run_process_action_callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `send'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `run_callbacks'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
activesupport (3.0.3) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rescue.rb:17:in `process_action'
newrelic_rpm (2.13.4) lib/new_relic/agent/instrumentation/rails3/action_controller.rb:34:in `process_action'
newrelic_rpm (2.13.4) lib/new_relic/agent/instrumentation/controller_instrumentation.rb:252:in `perform_action_with_newrelic_trace'
newrelic_rpm (2.13.4) lib/new_relic/agent/method_tracer.rb:141:in `trace_execution_scoped'
newrelic_rpm (2.13.4) lib/new_relic/agent/instrumentation/controller_instrumentation.rb:247:in `perform_action_with_newrelic_trace'
newrelic_rpm (2.13.4) lib/new_relic/agent/instrumentation/rails3/action_controller.rb:33:in `process_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:120:in `process'
actionpack (3.0.3) lib/abstract_controller/rendering.rb:40:in `process'
actionpack (3.0.3) lib/action_controller/metal.rb:138:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal.rb:178:in `action'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:27:in `call'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:148:in `call'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:93:in `recognize'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:75:in `optimized_each'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:92:in `recognize'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:139:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:492:in `call'
newrelic_rpm (2.13.4) lib/new_relic/rack/developer_mode.rb:20:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/head.rb:14:in `call'
rack (1.2.1) lib/rack/methodoverride.rb:24:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/flash.rb:182:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/cookies.rb:295:in `call'
activerecord (3.0.3) lib/active_record/query_cache.rb:32:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:12:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:31:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:353:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:46:in `call'
activesupport (3.0.3) lib/active_support/callbacks.rb:415:in `_run_call_callbacks'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:44:in `call'
rack (1.2.1) lib/rack/sendfile.rb:107:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call'
railties (3.0.3) lib/rails/rack/logger.rb:13:in `call'
rack (1.2.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.0.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.2.1) lib/rack/lock.rb:11:in `call'
rack (1.2.1) lib/rack/lock.rb:11:in `synchronize'
rack (1.2.1) lib/rack/lock.rb:11:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/static.rb:30:in `call'
railties (3.0.3) lib/rails/application.rb:168:in `call'
railties (3.0.3) lib/rails/application.rb:77:in `send'
railties (3.0.3) lib/rails/application.rb:77:in `method_missing'
railties (3.0.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.2.1) lib/rack/content_length.rb:13:in `call'
rack (1.2.1) lib/rack/handler/webrick.rb:52:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:开发者_如何学Python173:in `start_thread'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:82:in `start'
rack (1.2.1) lib/rack/handler/webrick.rb:13:in `run'
rack (1.2.1) lib/rack/server.rb:213:in `start'
railties (3.0.3) lib/rails/commands/server.rb:65:in `start'
railties (3.0.3) lib/rails/commands.rb:30
railties (3.0.3) lib/rails/commands.rb:27:in `tap'
railties (3.0.3) lib/rails/commands.rb:27
script/rails:6:in `require'
script/rails:6

The server logs show this:

Started GET "/posts" for 127.0.0.1 at Sat Jul 02 22:34:51 -0700 2011
  Processing by PostsController#index as HTML

... SQL statements ...

Rendered layouts/_stylesheets.html.erb (1.9ms)
Rendered layouts/_header.html.erb (4.4ms)
Rendered layouts/_footer.html.erb (1.5ms)
Rendered posts/index.html.erb within layouts/application (18.5ms)
Completed   in 408ms

ArgumentError (wrong number of arguments (0 for 1)):

Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.3/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.0ms)
Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.3/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (26.5ms)
Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.3/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (31.5ms)

I have no idea where to begin debugging this. I have many other complicated controllers in this app and have never faced this issue with them, so I am pretty sure it something very dumb. The logic in the index action works without the index.html.erb file (hence I get all the way to the template missing message). But as soon as I add an index.html.erb file, I get the arguments error. I am pretty lost with this.

Thanks!

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