我正在开发 Devise + 主动存储，需要一种方法 ActiveStorage::Blob#open目前仅在 rails 6 vdersion 中可用，因此将 rails 5.2 升级到 rails 6.0.0.alpha。升级后我收到此错误。我尝试了许多解决方案，但没有一个有效。
Started GET "/admins/sign_in" for 127.0.0.1 at 2018-06-05 08:23:21 +0530
(1.9ms) SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
↳ /home/rotlu_crush/.rvm/gems/ruby-2.4.1/gems/activerecord-5.2.0/lib/active_record/log_subscriber.rb:98
ActionController::RoutingError (undefined local variable or method `mimes_for_respond_to' for DeviseController:Class):
devise (4.4.3) app/controllers/devise_controller.rb:18:in `<class:DeviseController>'
devise (4.4.3) app/controllers/devise_controller.rb:4:in `<main>'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:100:in `load'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:100:in `load'
activesupport (5.2.0) lib/active_support/dependencies.rb:468:in `block in load_file'
activesupport (5.2.0) lib/active_support/dependencies.rb:653:in `new_constants_in'
activesupport (5.2.0) lib/active_support/dependencies.rb:467:in `load_file'
activesupport (5.2.0) lib/active_support/dependencies.rb:365:in `block in require_or_load'
activesupport (5.2.0) lib/active_support/dependencies.rb:37:in `block in load_interlock'
activesupport (5.2.0) lib/active_support/dependencies/interlock.rb:14:in `block in loading'
activesupport (5.2.0) lib/active_support/concurrency/share_lock.rb:151:in `exclusive'
activesupport (5.2.0) lib/active_support/dependencies/interlock.rb:13:in `loading'
activesupport (5.2.0) lib/active_support/dependencies.rb:37:in `load_interlock'
activesupport (5.2.0) lib/active_support/dependencies.rb:348:in `require_or_load'
activesupport (5.2.0) lib/active_support/dependencies.rb:502:in `load_missing_constant'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/active_support.rb:43:in `load_missing_constant'
activesupport (5.2.0) lib/active_support/dependencies.rb:193:in `const_missing'
devise (4.4.3) app/controllers/devise/sessions_controller.rb:3:in `<main>'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:100:in `load'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:100:in `load'
activesupport (5.2.0) lib/active_support/dependencies.rb:468:in `block in load_file'
activesupport (5.2.0) lib/active_support/dependencies.rb:653:in `new_constants_in'
activesupport (5.2.0) lib/active_support/dependencies.rb:467:in `load_file'
activesupport (5.2.0) lib/active_support/dependencies.rb:365:in `block in require_or_load'
activesupport (5.2.0) lib/active_support/dependencies.rb:37:in `block in load_interlock'
activesupport (5.2.0) lib/active_support/dependencies/interlock.rb:14:in `block in loading'
activesupport (5.2.0) lib/active_support/concurrency/share_lock.rb:151:in `exclusive'
activesupport (5.2.0) lib/active_support/dependencies/interlock.rb:13:in `loading'
activesupport (5.2.0) lib/active_support/dependencies.rb:37:in `load_interlock'
activesupport (5.2.0) lib/active_support/dependencies.rb:348:in `require_or_load'
activesupport (5.2.0) lib/active_support/dependencies.rb:502:in `load_missing_constant'
bootsnap (1.3.0) lib/bootsnap/load_path_cache/core_ext/active_support.rb:43:in `load_missing_constant'
activesupport (5.2.0) lib/active_support/dependencies.rb:193:in `const_missing'
activesupport (5.2.0) lib/active_support/inflector/methods.rb:285:in `const_get'
activesupport (5.2.0) lib/active_support/inflector/methods.rb:285:in `block in constantize'
activesupport (5.2.0) lib/active_support/inflector/methods.rb:281:in `each'
activesupport (5.2.0) lib/active_support/inflector/methods.rb:281:in `inject'
activesupport (5.2.0) lib/active_support/inflector/methods.rb:281:in `constantize'
activesupport (5.2.0) lib/active_support/dependencies.rb:574:in `get'
activesupport (5.2.0) lib/active_support/dependencies.rb:605:in `constantize'
actionpack (5.2.0) lib/action_dispatch/http/request.rb:88:in `controller_class_for'
actionpack (5.2.0) lib/action_dispatch/http/request.rb:81:in `controller_class'
actionpack (5.2.0) lib/action_dispatch/routing/route_set.rb:46:in `controller'
actionpack (5.2.0) lib/action_dispatch/routing/route_set.rb:32:in `serve'
actionpack (5.2.0) lib/action_dispatch/routing/mapper.rb:18:in `block in <class:Constraints>'
actionpack (5.2.0) lib/action_dispatch/routing/mapper.rb:48:in `serve'
actionpack (5.2.0) lib/action_dispatch/journey/router.rb:52:in `block in serve'
actionpack (5.2.0) lib/action_dispatch/journey/router.rb:35:in `each'
actionpack (5.2.0) lib/action_dispatch/journey/router.rb:35:in `serve'
actionpack (5.2.0) lib/action_dispatch/routing/route_set.rb:840:in `call'
rack-pjax (1.0.0) lib/rack/pjax.rb:12:in `call'
remotipart (1.4.2) lib/remotipart/middleware.rb:32:in `call'
warden (1.2.7) lib/warden/manager.rb:36:in `block in call'
warden (1.2.7) lib/warden/manager.rb:35:in `catch'
warden (1.2.7) lib/warden/manager.rb:35:in `call'
rack (2.0.5) lib/rack/tempfile_reaper.rb:15:in `call'
rack (2.0.5) lib/rack/etag.rb:25:in `call'
rack (2.0.5) lib/rack/conditional_get.rb:25:in `call'
rack (2.0.5) lib/rack/head.rb:12:in `call'
actionpack (5.2.0) lib/action_dispatch/http/content_security_policy.rb:18:in `call'
rack (2.0.5) lib/rack/session/abstract/id.rb:232:in `context'
rack (2.0.5) lib/rack/session/abstract/id.rb:226:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/cookies.rb:670:in `call'
activerecord (5.2.0) lib/active_record/migration.rb:559:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (5.2.0) lib/active_support/callbacks.rb:98:in `run_callbacks'
actionpack (5.2.0) lib/action_dispatch/middleware/callbacks.rb:26:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:61:in `call'
web-console (3.6.2) lib/web_console/middleware.rb:135:in `call_app'
web-console (3.6.2) lib/web_console/middleware.rb:30:in `block in call'
web-console (3.6.2) lib/web_console/middleware.rb:20:in `catch'
web-console (3.6.2) lib/web_console/middleware.rb:20:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
railties (5.2.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (5.2.0) lib/rails/rack/logger.rb:26:in `block in call'
activesupport (5.2.0) lib/active_support/tagged_logging.rb:71:in `block in tagged'
activesupport (5.2.0) lib/active_support/tagged_logging.rb:28:in `tagged'
activesupport (5.2.0) lib/active_support/tagged_logging.rb:71:in `tagged'
railties (5.2.0) lib/rails/rack/logger.rb:26:in `call'
sprockets-rails (3.2.1) lib/sprockets/rails/quiet_assets.rb:13:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/request_id.rb:27:in `call'
rack (2.0.5) lib/rack/method_override.rb:22:in `call'
rack (2.0.5) lib/rack/runtime.rb:22:in `call'
activesupport (5.2.0) lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (5.2.0) lib/action_dispatch/middleware/static.rb:127:in `call'
rack (2.0.5) lib/rack/sendfile.rb:111:in `call'
railties (5.2.0) lib/rails/engine.rb:524:in `call'
puma (3.11.4) lib/puma/configuration.rb:225:in `call'
puma (3.11.4) lib/puma/server.rb:632:in `handle_request'
puma (3.11.4) lib/puma/server.rb:446:in `process_client'
puma (3.11.4) lib/puma/server.rb:306:in `block in run'
puma (3.11.4) lib/puma/thread_pool.rb:120:in `block in spawn_thread'
宝石文件：
ruby '2.4.1'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
# gem 'rails', '~> 5.2.0'
gem "rails", github: "rails/rails"
# Use postgresql as the database for Active Record
gem 'pg', '>= 0.18', '< 2.0'
# Use Puma as the app server
gem 'puma', '~> 3.11'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'mini_racer', platforms: :ruby
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.5'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use ActiveStorage variant
# gem 'mini_magick', '~> 4.8'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
#
gem 'figaro'
gem 'devise'
# gem 'rails_admin', github: 'dtcristo/rails_admin', branch: 'active_storage'
gem 'rails_admin', github: 'dtcristo/rails_admin', branch: 'active_storage'
# gem 'rails_admin'
gem 'rails_admin_rollincode'
# gem "wysiwyg-rails"
gem "activerecord-import"
gem "simple_xlsx_reader"
如果有人遇到同样的问题，请帮助解决此问题。