How to `bundle install` when your Gemfile requires an older version of bundler?

Solution 1:

First you need to install the appropriate version of bundler:

% gem install bundler -v '~> 1.0.0'
Successfully installed bundler-1.0.22

Then force rubygems to use the version you want (see this post):

% bundle _1.0.22_ install

Solution 2:

The error message In Gemfile: bundler (~> 1.16) is a bit inaccurate, since the version number requirement can come from other places, such as the .gemspec file, which was the case for me:

spec.add_development_dependency "bundler", "~> 1.16"

Removing the version number from the .gemspec file solved the issue for me:

spec.add_development_dependency "bundler"