Redmine

Hello,

We currently run Redmine 3.4.6 with a lot of custom plugins. It's a production environment with hundreds of users.
Is there a way to gradually upgrade Redmine through the different minor versions, from 3.4.6 to 3.4.13, and then on to 4.0.0 and up?

Thanks for any advice you can provide!
Anas

Information
Redmine 3.4.6.stable

Default administrator account changed    
Attachments directory writable    
Plugin assets directory writable (./public/plugin_assets)    
RMagick available (optional)    
ImageMagick convert available (optional)    

Environment:
  Redmine version                3.4.6.stable
  Ruby version                   2.4.2-p198 (2017-09-14) [x86_64-linux]
  Rails version                  4.2.8
  Environment                    production
  Database adapter               Mysql2
SCM:
  Git                            1.9.1
  Filesystem                     
Redmine plugins:
  activity_by_issue_status       0.0.4
  auto_populate_checklists       0.0.1
  clipboard_image_paste          1.13
  globalme_attachments           0.0.2
  globalme_dev_tracker           0.0.1
  globalme_projects_widget       
  group_issue_visibility         0.0.1
  issue_status_sort              0.0.2
  multi_link_formatter           0.0.1
  redmine_agile                  1.5.2
  redmine_auto_fields            0.0.3
  redmine_backlogs               v1.0.6
  redmine_checklists             3.1.9
  redmine_collapsible_projects   0.0.1
  redmine_custom_reports         0.1.5
  redmine_custom_values_projects 0.0.1
  redmine_download_link          0.0.1
  redmine_elasticsearch          0.2.1
  redmine_embedded_video         0.0.3.1
  redmine_googlesss              0.0.2
  redmine_impasse                1.3.1
  redmine_import_user_to_group   0.0.6
  redmine_importer               1.2.2
  redmine_issue_callbacks        0.0.1
  redmine_issue_history          0.0.1
  redmine_issue_relations        0.2.0
  redmine_issue_templates        0.2.0
  redmine_issue_tracker          0.0.1
  redmine_issues_macros          0.0.1
  redmine_ldap                   0.0.1
  redmine_mail_notifications     0.2.0
  redmine_mentions               0.0.3
  redmine_mypage_projects        0.0.1
  redmine_omniauth_google        0.0.1
  redmine_pin_comment            0.0.1
  redmine_plugin_views_revisions 0.0.1
  redmine_project_admin          0.2.0
  redmine_project_watchers       0.0.1
  redmine_remove_watchers        0.0.1
  redmine_resque                 0.0.4
  redmine_share_forums           0.0.1
  redmine_update_tickets_csv     0.0.1
  redmine_user_ratings           0.0.1
  restrict_time_logging          0.0.1
  status_button                  0.1.0
  workflow_column                0.0.1