ruby on rails - ActionController::UnknownFormat in htmltoword gem -

i using htmltoword gem here https://github.com/karnov/htmltoword , followed steps that. here error when running controller

error is

actioncontroller::unknownformat in htmltopdfccontroller#show

my controller code

class htmltopdfccontroller < applicationcontroller   def show         respond_to |format|         format.docx         file = htmltoword::document.create params[:docx_html_source], "file_name.docx"         send_file file.path, :disposition => "attachment"         end     end   end end 

help me out.