/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require' -- while trying to start the server

I end up with this error - /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in 'require'

I am using a vagrant environment and this is the flow of executing the commands

vagrant up
vagrant ssh
cd /vagrant/
bundle
rake db:create
rake db:migrate
rspec spec //for the tests

and rails s for running it.