ArgumentError in Rails::MailersController#preview

Question

I am working on 10 chapter in The Ruby on Rails Tutorial by Michael Hartl, I am facing the issue regarding account activation

Missing host to link to! Please provide the :host parameter, set default_url_options[:host], or set :only_path to true

user_mailer.rb

class UserMailer < ApplicationMailer

  def account_activation(user)
    @user = user
    mail to: user.email, subject: "Account activation"
  end

  def password_reset
    @greeting = "Hi"
    mail to: user.email
  end
end

account_activation.html.erb

<h1>Sample App</h1>

<p>Hi <%= @user.name %>,</p>

<p>
Welcome to the Sample App! Click on the link below to activate your account:
</p>

<%= link_to "Activate", edit_account_activation_url(@user.activation_token,
                                                    email: @user.email) %>

app/views/user_mailer/account_activation.html.erb:9:in `_app_views_user_mailer_account_activation_html_erb__2222007018826719766_70083837842380'
app/mailers/user_mailer.rb:5:in `account_activation'

Answer 1

UPDATE

Add default_url_options to config/environments/development.rb

config.action_mailer.default_url_options = { :host => '127.0.0.1', :port => 3000 }

OR

config.action_mailer.default_url_options = { :host => 'localhost', :port => 3000 }