Rails SystemStackError (stack level too deep) in actionpack

today I got to an error with my Ruby on Rails API and I can't figure out what the problem is. Whenever I try to create a new Character in my Controller I always get an SystemStackError and I have no Idea why. I will post the relevant Files below.

characters_controller.rb

module Api
module V1
    class CharactersController < ApplicationController
        def index
            @chars = Character.all
            respond_to do |format|
                format.json { render :json => @chars }
            end
        end
        def create
            @newchar = Character.new

            lastmod = params[:lastModified]
            charname = params[:name]
            realm = params[:realm]
            battlegroup = params[:battlegroup]
            charclass = params[:class]
            race = params[:race]
            gender = params[:gender]
            level = params[:level]
            achievement_points = params[:achievementPoints]
            thumbnailurl = params[:thumbnailurl]
            itemlvltotal = params[:itemleveltotal]
            itemlvlequipped = params[:itemlevelequipped]
            userid = params[:userid]

            @newchar.lastModified = lastmod
            @newchar.name = charname
            @newchar.realm = realm
            @newchar.battlegroup = battlegroup
            @newchar.class = charclass
            @newchar.race = race
            @newchar.gender = gender
            @newchar.level = level
            @newchar.achievementPoints = achievement_points
            @newchar.thumbnailurl = thumbnailurl
            @newchar.itemleveltotal = itemlvltotal
            @newchar.itemlevelequipped = itemlvlequipped
            @newchar.userid = userid

            if @newchar.save!
                render json: {status: 'success', code: 0, message: 'Character has been saved'}
            else
                render json: {status: 'error', code: 1, message: 'Failed to save character'}
            end
        end
        def update 
        end
        def mychars
            @chars = Character.where(userid: params[:userid])
            render json: {characters: @chars}
        end
    end
end
end

routes.rb

Rails.application.routes.draw do
 namespace :api, :defaults => {:format => :json} do
namespace :v1 do

    resources :users do
    collection do
      post 'register'
      post 'login'
      get 'make_moderator'
    end
  end

  resources :raids do
    collection do
      post 'create'
      get 'details'
      post 'sign_up'
      post 'sign_off'
      post 'signedup'
    end
  end

  resources :characters do
    collection do
      get 'mychars'
      post 'create'
      post 'update'
    end
  end

  end
 end
end

character.rb (my model)

class Character < ActiveRecord::Base
   belongs_to :user
end

The error (stacktrace) I get is:

Started POST "/api/v1/characters/create" for 82.112.107.65 at 2015-01-07 17:30:10 +0100
  ActiveRecord::SchemaMigration Load (0.2ms)  SELECT "schema_migrations".* FROM     "schema_migrations"
Processing by Api::V1::CharactersController#create as JSON
  Parameters: {"lastModified"=>"1194551616", "name"=>"Mortan", "realm"=>"Kargath",     "battlegroup"=>"Reckoning / Abrechnung", "class"=>"5", "race"=>"4", "gender"=>"0", "level"=>"72", "achievementPoints"=>"7245", "thumbnailurl"=>"http://eu.battle.net/static-render/eu/kargath/240/386800-avatar.jpg", "itemleveltotal"=>"137", "itemlevelequipped"=>"127", "userid"=>"10"}
Completed 500 Internal Server Error in 26ms

SystemStackError (stack level too deep):
  actionpack (4.1.8) lib/action_dispatch/middleware/reloader.rb:79


  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-    4.1.8/lib/action_dispatch/middleware/templates/rescues/_source.erb (0.9ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (1.8ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.8ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (29.0ms)

Any help is appreciated since I don't know how to handle this problem :) thanks

EDIT: Whenever I try to send the same request again I get a different error:

NoMethodError (undefined method `[]' for nil:NilClass):
  app/controllers/api/v1/characters_controller.rb:11:in `create'


  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_source.erb (1.2ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (2.2ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.8ms)
  Rendered /usr/local/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (28.3ms)

Where line 11 is:

@newchar = Character.new

The answer to this problem was to rename the attribute of Character named class. This has somehow caused the error and after changing it the problem was gone. Thanks to everyone who helped me with this problem.