ruby on rails - wrong number of arguments (3 for 2) in form_for method -

i'm upgraded rails 3.2.13 , i'm migrating old app run in new environment (ruby1.9.3). app ran fine ruby192 , rails 3.0.0.

i receiving error when trying create new record (a firefighter)

wrong number of arguments (3 2)

and here code form

<%= form_for :fire_fighter, @fire_fighter, :url => { :action => "create" } |f| %> 

based on reading other posts, recommend remove "fire_fighter" this

<%= form_for :@fire_fighter, :url => { :action => "create" } |f| %> 

this did allow page render when tried enter fill in text fields , submit or create record in database error message built app says:

all of fields setup strings.

oh , had fields filled out before hit submit. i'm stuck.

any appreciated thanks.

although answer may change when post page source code , rest of form code, trying create symbol instance variable.

<%= form_for :@fire_fighter, :url => { :action => "create" } |f| %> 

notice :@fire_fighter. should @fire_fighter. correct code should be

<%= form_for @fire_fighter, :url => { :action => "create" } |f| %> 

the reason why use instance variable @fire_fighter because in controller there should

def new   @fire_fighter = firefighter.new end 

that way, form directly grabbing instance variable controller onto form. symbols don't transverse controllers views, instance variables do, hence use of @fire_fighter first argument in form_for method.