Migrating gitlab installed by helm to omnibus-gitlab,Object Storage is not enabled

Hi everyone, I know this problem exists in the documentation。
But my problem is more complicated。

I have a gitlab installed by helm,and used object storage by cephfs
gitlab version 11.9.8
This is some configuration in the configuration file

    storageClass: cephfs
    size: 500Gi
      cpu: 1000m
      memory: 2Gi
      cpu: 50m
      memory: 350Mi

I entered the docker and executed the following command

gitlab-rake gitlab:backup:create

then,restore in the server installed omnibus-gitlab ,and is the same verison。
The difference is that using local storage in omnibus-gitlab
put the backup file into the ‘backup_path’ what edit in /etc/gitlab.rb

gitlab-ctl stop unicorn
gitlab-ctl stop sidekiq
gitlab-rake gitlab:backup:restore BACKUP=1588947812_2020_05_08_11.9.8
gitlab-ctl start
gitlab-rake gitlab:check SANITIZE=true

And it’s worked !
But here is the problem !
when i access ‘system hooks’ or ‘/admin/groups’ it’s return 500.

Started GET "/admin/groups" for at 2020-05-11 11:23:42 +0800
Processing by Admin::GroupsController#index as HTML
Completed 500 Internal Server Error in 172ms (ActiveRecord: 14.3ms)
ActionView::Template::Error (Object Storage is not enabled):
    23:       = visibility_level_icon(group.visibility_level, fw: false)
    25:   .avatar-container.rect-avatar.s40
    26:     = group_icon(group, class: "avatar s40 d-none d-sm-block")
    27:   .title
    28:     = link_to [:admin, group], class: 'group-name' do
    29:       = group.full_name
app/uploaders/object_storage.rb:390:in `storage_for'
app/uploaders/object_storage.rb:229:in `object_store='
app/uploaders/object_storage.rb:64:in `upload='
app/uploaders/object_storage.rb:49:in `retrieve_from_store!'
app/models/concerns/avatarable.rb:57:in `uncached_avatar_path'
app/models/concerns/avatarable.rb:53:in `avatar_path'
app/models/concerns/avatarable.rb:24:in `avatar_url'
app/helpers/avatars_helper.rb:114:in `source_icon'
app/helpers/avatars_helper.rb:9:in `group_icon'
app/views/admin/groups/_group.html.haml:26:in `_app_views_admin_groups__group_html_haml___2364090223597980464_70264417591840'
app/views/admin/groups/index.html.haml:18:in `_app_views_admin_groups_index_html_haml___1908539934592158426_70264413756160'
app/controllers/application_controller.rb:116:in `render'
lib/gitlab/i18n.rb:55:in `with_locale'
lib/gitlab/i18n.rb:61:in `with_user_locale'
app/controllers/application_controller.rb:434:in `set_locale'
lib/gitlab/middleware/rails_queue_duration.rb:27:in `call'
lib/gitlab/metrics/rack_middleware.rb:17:in `block in call'
lib/gitlab/metrics/transaction.rb:55:in `run'
lib/gitlab/metrics/rack_middleware.rb:17:in `call'
lib/gitlab/middleware/multipart.rb:103:in `call'
lib/gitlab/request_profiler/middleware.rb:16:in `call'
lib/gitlab/middleware/go.rb:20:in `call'
lib/gitlab/etag_caching/middleware.rb:13:in `call'
lib/gitlab/middleware/correlation_id.rb:16:in `block in call'
lib/gitlab/correlation_id.rb:15:in `use_id'
lib/gitlab/middleware/correlation_id.rb:15:in `call'
lib/gitlab/middleware/read_only/controller.rb:40:in `call'
lib/gitlab/middleware/read_only.rb:18:in `call'
lib/gitlab/middleware/basic_health_check.rb:25:in `call'
lib/gitlab/request_context.rb:26:in `call'
lib/gitlab/metrics/requests_rack_middleware.rb:29:in `call'
lib/gitlab/middleware/release_env.rb:13:in `call'

I know there has instructions in the documentation

Migrating from object storage to local storage

In Omnibus installations:

In order to migrate back to local storage:

  1. Set both direct_upload and background_upload to false in gitlab.rb , under the artifacts object storage settings.
  2. Reconfigure GitLab.
  3. Run gitlab-rake gitlab:artifacts:migrate_to_local .
  4. Disable object_storage for artifacts in gitlab.rb :
  • Set gitlab_rails['artifacts_object_store_enabled'] = false .
  • Comment out all other artifacts_object_store settings, including the entire artifacts_object_store_connection section, including the closing } .
  1. [Reconfigure GitLab]
    (How to restart GitLab | GitLab)

But When i execute this command

# gitlab-rake gitlab:artifacts:migrate_to_local    
rake aborted!
    Don't know how to build task 'gitlab:artifacts:migrate_to_local' (See the list of available tasks with `rake --tasks`)
    Did you mean?  gitlab:artifacts:migrate
    /opt/gitlab/embedded/bin/bundle:23:in `load'
    /opt/gitlab/embedded/bin/bundle:23:in `<main>'
    (See full trace by running task with --trace)

So, what can i do 。help me please,thanks