CD to the project root where the file "Gemfile" exists, and run these commands: sudo gem install bundler bundler install

1- Download the latest stable version: https://www.ruby-lang.org/en/downloads/ -------------------------------------------------------------------------- 2- apt install build-essential zlib1g-dev libssl-dev sqlite3 libsqlite3-dev nodejs -------------------------------------------------------------------------- 3- tar xvf ruby-2.4.0.tar.gz ./configure --with-openssl-dir=/usr/lib/ssl make sudo make install --------------------------------------------------------------------------