title: Unable to convert unpermitted parameters to hash
body: <p>I've followed multiple stack overflow posts regarding this same issue, but I don't think I have the rails proficiency to know how to apply these fixes to my code.</p>
  <p>Been following an old railscast show: <a href="http://railscasts.com/episodes/217-multistep-forms" rel="nofollow noreferrer">http://railscasts.com/episodes/217-multistep-forms</a></p>
  <p>And I'm aware that the issue is something to do with permitting objects/hashes but I just don't understand it all.</p>
  <p>The error I'm getting is from this line of code in my controller:</p>
  <pre><code>session[:zerch_params].deep_merge!(params[:zerch]) if params[:zerch]
  </code></pre>
  <p><strong>Controller</strong>
  class ZerchesController &lt; InheritedResources::Base</p>
  <pre><code>def index
      @zerches = Zerch.all
  end
  
  def show
      @zerch = Zerch.find(params[:id])
  end
  
  def new
      session[:zerch_params] ||= {}
      @zerch = Zerch.new(session[:zerch_params])
      @zerch.current_step = session[:zerch_step]
  end
  
  def create
      session[:zerch_params].deep_merge!(params[:zerch]) if params[:zerch]
      @zerch = Zerch.new(session[:zerch_params])
      @zerch.current_step = session[:zerch_step]
      if @zerch.valid?
          if params[:back_button]
              @zerch.previous_step
          elsif @zerch.last_step?
              @zerch.save if @zerch.all_valid?
          else            
              @zerch.next_step
          end
          session[:zerch_step] = @zerch.current_step
  end
  if @zerch.new_record?
      render &quot;new&quot;
  else
      session[:zerch_step] = session[:zerch_params] = nil
      flash[:notice] = &quot;zerch complete!&quot;
      redirect_to @zerch
  end
  end
  
  
  
  
  private
  
  def zerch_params
    params.require(:zerch).permit(:location, :category, :price)
  end
  
  end
  </code></pre>