rails admin設定後、/adminにいこうとしたら、undefined local variable or method `warden' for #<RailsAdmin::MainCont

rails admin設定後、/adminにいこうとしたら、
undefined local variable or method `warden' for #RailsAdmin::MainController:0x000000000fc5e180 Did you mean? warn
というエラーがでてしまいました。
どこを直したらいいのでしょうか。ご教授ください。お願いします。

ruby
1RailsAdmin.config do |config|
2
3  ### Popular gems integration
4
5  ## == Devise ==
6   config.authenticate_with do
7     warden.authenticate! scope: :user
8   end
9   config.current_user_method(&:current_user)
10
11  ## == CancanCan ==
12   config.authorize_with :cancancan
13
14  ## == Pundit ==
15  # config.authorize_with :pundit
16
17  ## == PaperTrail ==
18  # config.audit_with :paper_trail, 'User', 'PaperTrail::Version' # PaperTrail >= 3.0.0
19
20  ### More at https://github.com/sferik/rails_admin/wiki/Base-configuration
21
22  ## == Gravatar integration ==
23  ## To disable Gravatar integration in Navigation Bar set to false
24  # config.show_gravatar = true
25
26  config.actions do
27    dashboard                     # mandatory
28    index                         # mandatory
29    new
30    export
31    bulk_delete
32    show
33    edit
34    delete
35    show_in_app
36
37    ## With an audit adapter, you can add:
38    # history_index
39    # history_show
40  end
41end
42