how to handle authorize! :update, @post ArgumentError in rails cancancan gem

Question

I want to grant all permission to admin, and only read permission to normal user. so, after hitting /posts/1/edit for admin its working fine, but for normal user its giving

ArgumentError in PostsController#edit
wrong number of arguments (given 2, expected 0..1)

Application_Controller.rb

class ApplicationController < ActionController::Base
    before_action :configure_permitted_parameters, if: :devise_controller?

    protect_from_forgery with: :exception

    rescue_from CanCan::AccessDenied do
      flash[:error] = 'Access denied!'
      redirect_to root_url
    end

  protected

  def configure_permitted_parameters
    added_attrs = [:first_name, :last_name, :phone, :gender, :username, :email, :password, :password_confirmation, :remember_me]
    devise_parameter_sanitizer.permit :sign_up, keys: added_attrs
    devise_parameter_sanitizer.permit :sign_in, keys: [:login, :password]
    devise_parameter_sanitizer.permit :account_update, keys: added_attrs
  end

end

Post_controller.rb

class PostsController < ApplicationController
  before_action :authenticate_user!
  before_action :fetch_all_posts_and_users


  #some code

  def edit
    @post = Post.find(params[:id])
    authorize! :update, @post
  end

  def update
    @post = Post.find(params[:id])
    if @post.update(post_params)
      redirect_to(post_path(@post))
    else
      render('edit')
    end
  end

  def destroy
    @post = Post.find(params[:id])
    @post.destroy
  end

  

  private

  def post_params
    params.require(:post).permit(:title, :image, :total_likes)
  end

  def fetch_all_posts_and_users
    @posts = Post.all
    @users = User.all
  end




end

I had also add load_and_authorize_resource but its not working for both admin and normal user

Ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
      user ||= User.new # guest user (not logged in)

       if user.admin?
         can :manage, :all
       else
        can :read, :all
       end

  end
end