bootstrap-sprocketsをインポートするとエラーが起きる

前提・実現したいこと

ここに質問の内容を詳しく書いてください。
railsのデザインにてbootstrapを用いています。
デザインのカスタマイズをしたくbootstrap-sprocketsを入れたいのですが、
application.scssに@import "bootstrap-sprockets";を記載したら
以下のエラーメッセージが発生しました。

発生している問題・エラーメッセージ

Sass::SyntaxError in Payments#index
Showing /Users/tatsukawayoshitaka/kakeibo_app/app/views/layouts/application.html.erb where line #17 raised:

File to import not found or unreadable: bootstrap-sprockets.
Load paths:
  /Users/tatsukawayoshitaka/kakeibo_app/app/assets/config
  /Users/tatsukawayoshitaka/kakeibo_app/app/assets/images
  /Users/tatsukawayoshitaka/kakeibo_app/app/assets/javascripts
  /Users/tatsukawayoshitaka/kakeibo_app/app/assets/stylesheets
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/jquery-rails-4.3.5/vendor/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/coffee-rails-4.2.2/lib/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/actioncable-5.2.3/lib/assets/compiled
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activestorage-5.2.3/app/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/actionview-5.2.3/lib/assets/compiled
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/turbolinks-source-5.2.0/lib/assets/javascripts
  /Users/tatsukawayoshitaka/kakeibo_app/node_modules
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/popper_js-1.14.5/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/stylesheets
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/stylesheets
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/javascripts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/fonts
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/images
  /Users/tatsukawayoshitaka/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/bootstrap-4.1.3/assets/stylesheets

該当のソースコード

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
 * vendor/assets/stylesheets directory can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
 * files in this directory. Styles in this file should be added after the last require_* statement.
 * It is generally better to create a new file per style scope.
 *

 */

 @import "bootstrap-sprockets";
 @import "bootstrap";

試したこと

layouts内には以下も記載しています。
<%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
<%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>

補足情報（FW/ツールのバージョンなど）

以下のgemを入れております。
gem 'devise'
gem 'bootstrap', '~> 4.3.1'
gem 'bootstrap-sass'
gem 'autoprefixer-rails'
gem 'jquery-rails'

gem 'kaminari'
gem 'sprockets-rails', '2.3.3'