Tengo una forma simple como esta:

<form name="serachForm" method="post" action="/home/search">   
  <input type="text" name="searchText" size="15" value="">
  <input class="image" name="searchsubmit" value="Busca" src="/images/btn_go_search.gif" align="top" border="0" height="17" type="image" width="29">
</form>

Y un controlador con este método:

  def busca
    puts params[:searchText]
  end

Cuando hago un clic en el botón de imagen en el formulario, obtengo un ActionController :: InvalidAuthenticityToken. Aquí está el StackTrace completo:

/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/request_forgery_protection.rb:86:inverify_authenticity_token' /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/callbacks.rb:178:inenviar '/Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/callbacks.rb:178:inevaluate_method' /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/callbacks.rb:166:inllame a '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/filters.rb:225:incall' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/filters.rb:629:inrun_before_filters '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/filters.rb:615:incall_filters' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/filters.rb:610:inperform_action_without_benchmark '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/benchmarking.rb:68:inperform_action_without_rescue' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/benchmarking.rb:68:inperform_action_without_rescue '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/rescue.rb:136:inperform_action_without_caching' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/caching/sql_cache.rb:13:inrealizar_acción '/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/abstract/query_cache.rb:34:incache' /Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/query_cache.rb:8:incaché '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/caching/sql_cache.rb:12:inperform_action' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/base.rb:524:inenviar '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/base.rb:524:inprocess_without_filters' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/filters.rb:606:inprocess_without_session_management_support '/Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/session_management.rb:134:inprocess' /Library/Ruby/Gems/1.8/gems/actionpack-2.2.2/lib/action_controller/base.rb:392:inproceso '/Library/Ruby/Gems/1.8/gems/rails-2.2.2/lib/webrick_server.rb:74:inservice' /Library/Ruby/Gems/1.8/gems/rails-2.2.2/lib/commands/servers/webrick.rb:66 /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:inrequire '/Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:521:innew_constants_in' /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:inRequerir '/Library/Ruby/Gems/1.8/gems/rails-2.2.2/lib/commands/server.rb:49

¿Que esta pasando?