运行时rails server
,我加载此警告:
Gem::LoadError: Specified 'sqlite3' for database adapter, but the gem is not loaded. Add `gem 'sqlite3'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).
然而我的 gemfile 有 gem
group :development do
gem 'sqlite3'
是什么导致了这个错误?
从这里使用 Rails 更新说明https://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-4-2-to-rails-5-0