Ruby on Rails Mongrel error

When I click on the "about your application's environment" button on the "welcome" your riding rails page this happens in my server console.

** Starting Mongrel listening at 0.0.0.0:3000
** Starting Rails with development environment...
** Rails loaded.
** Loading any Rails specific GemPlugins
** Signals ready.  INT => stop (no restart).
** Mongrel 1.1.5 available at 0.0.0.0:3000
** Use CTRL-C to stop.
Sat Jul 17 02:24:28 -0400 2010: Error calling Dispatcher.dispatch #<NoMethodErro
r: You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.split>
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.8/lib/action_controll
er/cgi_process.rb:52:in `dispatch_cgi'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.8/lib/action_controll
er/dispatcher.rb:101:in `dispatch_cgi'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.8/lib/action_controll
er/dispatcher.rb:27:in `dispatch'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/rails.rb:76:in `process'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-msw开发者_开发问答in32-60/bin/../
lib/mongrel/rails.rb:74:in `synchronize'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/rails.rb:74:in `process'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:159:in `process_client'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:158:in `each'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:158:in `process_client'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:285:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:285:in `initialize'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:285:in `new'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:285:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:268:in `initialize'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:268:in `new'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel.rb:268:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/configurator.rb:282:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/configurator.rb:281:in `each'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/configurator.rb:281:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mon
grel_rails:128:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../
lib/mongrel/command.rb:212:in `run'
C:/INSTAN~1.0-W/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mon
grel_rails:281
C:/INSTAN~1.0-W/ruby/bin/mongrel_rails:19:in `load'
C:/INSTAN~1.0-W/ruby/bin/mongrel_rails:19

Here are the versions

C:\InstantRails-2.0-win\rails_apps>rails -v
Rails 2.3.8

C:\InstantRails-2.0-win\rails_apps>ruby -v
ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32]

C:\InstantRails-2.0-win\rails_apps>gem -v
1.3.7

C:\InstantRails-2.0-win\rails_apps>gem install mongrel
Successfully installed mongrel-1.1.5-x86-mswin32-60
1 gem installed
Installing ri documentation for mongrel-1.1.5-x86-mswin32-60...
Installing RDoc documentation for mongrel-1.1.5-x86-mswin32-60...

---

I'm not able to reproduce (I'm on Ruby 1.9.1 mingw32 right here), but line 52 of cgi_process.rb is calling

if headers.include?('Set-Cookie')
  headers['cookie'] = headers.delete('Set-Cookie').split("\n")
end

maybe try checking your session key and cookie settings in environment.rb, and try running ruby script/server webrick (instead of mongrel) to see if that is the issue.

I also know that "about your application" link blows up if you don't have a database created or setup in database.yml, so check that too.

---

This issue is discussed at great lengths on the Rails bugtracker. The ultimate fix seems to be "get with the times" and move to Rails 3.x, but for those of us who can't just yet, there is a workaround.

You can download this mongrel.rb into your config/initializers directory. That seems to make pages load, but resources (stylesheets, javascript) don't seem to be loading. I am investigating further, but wanted to throw this out there as a quick pointer in the right direction.

I will update this answer as I learn more.