How to fix "Your Ruby version is 2.3.0, but your Gemfile specified 2.2.5" while server starting

You better install Ruby 2.2.5 for compatibility. The Ruby version in your local machine is different from the one declared in Gemfile.

If you're using rvm:

rvm install 2.2.5
rvm use 2.2.5

else if you're using rbenv:

rbenv install 2.2.5
rbenv local 2.2.5

else if you can not change ruby version by rbenv, read here

If you have already installed 2.2.5 and set as current ruby version, but still showing the same error even if the Ruby version 2.3.0 is not even installed, then just install the bundler.

gem install bundler

and then:

bundle install

If you are using rbenv then make sure that you run the "rbenv rehash" command after you set local or global ruby version. It solved the issue for me.

rbenv rehash