uninitialized constant Faraday::Error::ConnectionFailed in elastic-search

I'm implementing elastic-search in rails by following this tutorial

https://iridakos.com/programming/2017/12/03/elasticsearch-and-rails-tutorial

And add these lines to my User.rb include Elasticsearch::Model include Elasticsearch::Model::Callbacks & also installed these two gems gem 'elasticsearch-model' gem 'elasticsearch-rails' but when I try to execute this command Post.import(force: true) it gives me an error

uninitialized constant Faraday::Error::ConnectionFailed