Facing issue uninitialized constant AWS::S3::Errors in rails4

gem 'paperclip', '~> 4.2'
gem 'aws-s3'
gem 'aws-sdk'

to upload images or any other document. I have these two models: employee.rb

class Employee < ActiveRecord::Base
  has_many :attachments, as: :attachable
  accepts_nested_attributes_for :attachments
end

and in attachment.rb

class Attachment < ActiveRecord::Base
  belongs_to :attachable, polymorphic: true
  has_attached_file :attach,
                    :storage => :s3,
                    :s3_credentials => '#{Rails.root}/config/s3.yml',
                    :url => ':s3_domain_url',
                    :path => '/contents/:id/:basename.:extension'
  validates_attachment_content_type :attach,:content_type => ['application/msword','application/pdf', 'image/jpg', 'image/jpeg', 'image/png', 'image/gif']
end

and in my employeeS_controller.rb

 def edit
    @employee = Employee.where(id: params[:id]).first
    @employee.attachments.build
  end

  def update
    @employee = Employee.where(id: params[:id]).first
    if @employee.update_attributes(employee_params)
      redirect_to @employee, notice: I18n.t('employee_updated')
    else
      p @employee.errors
      render :action => :edit
    end
  end


  private

  def employee_params
    params.require(:employee).permit(:email, :role, :department_id, :designation_id, :is_active, attachments_attributes: [:attach, :name])
  end

and in my employess/edit.html.erb

<%= f.fields_for :attachments do |attach|%>
              <%= attach.file_field :attach, :class => 'btn' %>
 <% end %>

Now when am submitting the form am getting this in my params

{"utf8"=>"✓", "_method"=>"patch", "authenticity_token"=>"4pq1y2qS0AAbO+C6O1Sp0qmKFFXG2KZtB4mvIgvK3CKJ0CI/5yAYDJArhjsEzu6lSm/LkRfBIJDpSzRZUxp+bQ==", "employee"=>{"email"=>"inventory@adroit.com", "role"=>"INVENTORY", "department_id"=>"6", "designation_id"=>"3", "is_active"=>"1", "attachments_attributes"=>{"0"=>{"attach"=>#, @original_filename="index.jpeg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"employee[attachments_attributes][0][attach]\"; filename=\"index.jpeg\"\r\nContent-Type: image/jpeg\r\n">}}, "action"=>"update", "controller"=>"employees", "id"=>"3"}

But its not saving in my database it gives me error NameError (uninitialized constant AWS::S3::Errors):

and my settings in s3.yml is

development:
  bucket: "test"
  access_key_id: "*************"
  secret_access_key: "*************"

production:
  bucket: "test"
  access_key_id: "*************"
  secret_access_key: "*************"

Now please guide where am missing I am not getting it. Thanks in advance.