sass::syntaxerror Undefined mixin 'border-radius'

[cerenaracli]

We upgraded our rails version from 4.2.10 to 5.0.7.We encountered a problem after upgrading the version.When we start our app, we are seeing the following console warning:

Sass::SyntaxError - Undefined mixin 'border-radius'.:
  app/views/welcome/homepage.html.haml:16:in `_app_views_welcome_homepage_html_haml__1663568661347282844_70003372442660'
  app/controllers/welcome_controller.rb:88:in `homepage'

%html{lang: I18n.locale}
  %head
    = stylesheet_link_tag 'bootstrap.min', 'landing-animate', 'publins-homepage-css'
    %link{:href => "https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/themes/smoothness/jquery-ui.css"}
    %link{:href => "https://fonts.googleapis.com/css?family=Aldrich", :rel => "stylesheet", :type => "text/css"}/

we got error on stylesheet_link_tag line. we created mixin.scss file in app/assets/stylesheets and imported mixin to bootstrap.min,landing-animate and publins-homepage-css but kept getting same error.
What are your thoughts on this warning?

Thank you very much!!!

System configuration
Rails version:5.0.7
Ruby version: 2.4.0
'bootstrap-sass', '~> 3.4'