Deviseがインストールできない

Question

セッション関連を作り直そうとUserモデルを作り直していて、deviseを入れたのですが
bundle installは成功したものの

rails generate devise:install
の後

/Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/inflector/methods.rb:261:in `const_get': uninitialized constant User (NameError)
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/inflector/methods.rb:261:in `block in constantize'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/inflector/methods.rb:259:in `each'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/inflector/methods.rb:259:in `inject'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/inflector/methods.rb:259:in `constantize'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise.rb:305:in `get'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/mapping.rb:81:in `to'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/mapping.rb:76:in `modules'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/mapping.rb:93:in `routes'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/mapping.rb:160:in `default_used_route'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/mapping.rb:70:in `initialize'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise.rb:335:in `new'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise.rb:335:in `add_mapping'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/rails/routes.rb:241:in `block in devise_for'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/rails/routes.rb:240:in `each'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/devise-4.2.1/lib/devise/rails/routes.rb:240:in `devise_for'
        from /Users/nishidaryu/RubymineProjects/share-tan/config/routes.rb:3:in `block in <top (required)>'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/actionpack-4.2.7/lib/action_dispatch/routing/route_set.rb:432:in `instance_exec'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/actionpack-4.2.7/lib/action_dispatch/routing/route_set.rb:432:in `eval_block'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/actionpack-4.2.7/lib/action_dispatch/routing/route_set.rb:410:in `draw'
        from /Users/nishidaryu/RubymineProjects/share-tan/config/routes.rb:1:in `<top (required)>'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:40:in `each'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:40:in `load_paths'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:16:in `reload!'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:26:in `block in updater'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/activesupport-4.2.7/lib/active_support/file_update_checker.rb:75:in `execute'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:27:in `updater'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/initializable.rb:30:in `instance_exec'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/initializable.rb:30:in `run'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/initializable.rb:55:in `block in run_initializers'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `call'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/initializable.rb:54:in `run_initializers'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/railties-4.2.7/lib/rails/application.rb:352:in `initialize!'
        from /Users/nishidaryu/RubymineProjects/share-tan/config/environment.rb:4:in `<top (required)>'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application.rb:92:in `preload'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application.rb:143:in `serve'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application.rb:131:in `block in run'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application.rb:125:in `loop'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application.rb:125:in `run'
        from /Users/nishidaryu/RubymineProjects/share-tan/vendor/bundl/ruby/2.3.0/gems/spring-2.0.1/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /Users/nishidaryu/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from -e:1:in `<main>'

rails generate devise User、rake db:migrateなどもエラーがでます。

Answer 1

http://stackoverflow.com/questions/19748113/after-destroying-user-model-cannot-add-user-model-back-in

同様のケースがありました。
route.rbから、devise_for :usersみたいに記載した行を削除すればいいそうです。