rails/rails — Issue #3985: Requests with X-Requested-With header but without Accept header cause error 500
Author: jgonera
Created: 2011-12-14 17:00:18+00:00
State: open

What I first thought was a capybara-webkit bug (https://github.com/thoughtbot/capybara-webkit/issues/228), seems to be Rails bug. In a Rails 3.1.3 app (you can clone https://github.com/jgonera/capybara-webkit-bug) make a request to controller's action with `X-Requested-With` header but without `Accept` header.

You can do it using `curl`:

curl --header "Accept: " --header "X-Requested-With: XMLHttpRequest" http://localhost:3000

Result:

```
undefined method `ref' for nil:NilClass

Full Trace:

activesupport (3.1.3) lib/active_support/whiny_nil.rb:48:in `method_missing'
actionpack (3.1.3) lib/action_controller/metal/rendering.rb:9:in `block in process_action'
actionpack (3.1.3) lib/action_controller/metal/rendering.rb:9:in `map'
actionpack (3.1.3) lib/action_controller/metal/rendering.rb:9:in `process_action'
actionpack (3.1.3) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.1.3) lib/active_support/callbacks.rb:416:in `_run__4339349177336074348__process_action__1443739901137356475__callbacks'
activesupport (3.1.3) lib/active_support/callbacks.rb:386:in `_run_process_action_callbacks'
activesupport (3.1.3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.1.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.1.3) lib/action_controller/metal/rescue.rb:17:in `process_action'
actionpack (3.1.3) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.1.3) lib/active_support/notifications.rb:53:in `block in instrument'
activesupport (3.1.3) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.1.3) lib/active_support/notifications.rb:53:in `instrument'
actionpack (3.1.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.1.3) lib/action_controller/metal/params_wrapper.rb:201:in `process_action'
activerecord (3.1.3) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.1.3) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.1.3) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.1.3) lib/action_controller/metal.rb:193:in `dispatch'
actionpack (3.1.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.1.3) lib/action_controller/metal.rb:236:in `block in action'
actionpack (3.1.3) lib/action_dispatch/routing/route_set.rb:65:in `call'
actionpack (3.1.3) lib/action_dispatch/routing/route_set.rb:65:in `dispatch'
actionpack (3.1.3) lib/action_dispatch/routing/route_set.rb:29:in `call'
rack-mount (0.8.3) lib/rack/mount/route_set.rb:152:in `block in call'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:96:in `block in recognize'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:75:in `optimized_each'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:95:in `recognize'
rack-mount (0.8.3) lib/rack/mount/route_set.rb:141:in `call'
actionpack (3.1.3) lib/action_dispatch/routing/route_set.rb:532:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.3.5) lib/rack/etag.rb:23:in `call'
rack (1.3.5) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/flash.rb:247:in `call'
rack (1.3.5) lib/rack/session/abstract/id.rb:195:in `context'
rack (1.3.5) lib/rack/session/abstract/id.rb:190:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/cookies.rb:331:in `call'
activerecord (3.1.3) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.1.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:477:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (3.1.3) lib/active_support/callbacks.rb:392:in `_run_call_callbacks'
activesupport (3.1.3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.1.3) lib/action_dispatch/middleware/callbacks.rb:28:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/reloader.rb:68:in `call'
rack (1.3.5) lib/rack/sendfile.rb:101:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
railties (3.1.3) lib/rails/rack/logger.rb:14:in `call'
rack (1.3.5) lib/rack/methodoverride.rb:24:in `call'
rack (1.3.5) lib/rack/runtime.rb:17:in `call'
activesupport (3.1.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.3.5) lib/rack/lock.rb:15:in `call'
actionpack (3.1.3) lib/action_dispatch/middleware/static.rb:53:in `call'
railties (3.1.3) lib/rails/engine.rb:456:in `call'
rack (1.3.5) lib/rack/content_length.rb:14:in `call'
railties (3.1.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.3.5) lib/rack/handler/webrick.rb:59:in `service'
/home/julas/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/home/julas/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/home/julas/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
```