Along with the e-book I mentioned, the author released a gem which you can add to your Rails 3 project. Resolving dependencies.......................................... By Ross Allen One of the major nerd goals for Airbnb in 2011 was upgrading to Rails 3.He installed Bundler using their Rails 2.3 guide and added any missing gems when trying to start the app.He used the recommended ~ notation for gem versions at first, but that upgraded our Paperclip gem to 2.3.3.And a thread between me and @tenderlove on twitter where he says he can reproduce it and isn't sure what the issue is, told me to open a ticket (also shows a screenshot of bundler resolving dependencies for a very long time) https://twitter.com/joemsak/status/850403632512208897 Finally, my gemfile with some notes commented at the top https://gist.github.com/joemsak/9e82361806fdcbb065626cabee822c70 For what it's worth, I use pessimize regularly to ensure my gem versions are kept in order to prevent accidental over-updates.Date: Sat Apr 8 2017 0000 Auto merge of #5559 - colby-swandale:gem-branch-exception, r=segiddins print an error message when a non-git gem is given a `branch` option When the user supplies the `branch` option to a non-git gem an error message should be printed. [[email protected] bundler (master)]$ ruby -v ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16] [[email protected] bundler (master)]$ cd ../bundle-issue [[email protected] bundle-issue]$ time ruby -I ~/git/bundler/lib ~/git/bundler/exe/bundle Fetching gem metadata from https://rubygems.org/.......The problem is trying to update the rails version to 4.2.2. The won't let me upgrade by bundle install and bundle upgrade rails keeps throwing this error: Could not find gem 'rails (= 4.2.2) ruby' in any of the gem sources listed in your Gemfile or installed on this machine.
This was our first step into Rails 3 land, and we did it at the end of 2010.Our production instances made the final switch in the week leading up to Thanksgiving, but it didn’t happen all at once.We added the required pieces throughout the past year, and, looking back, breaking the upgrade into three major steps was easier to manage than trying to cram it into a single deploy.(see  below for a larger discussion) In order to avoid this problem, when you update a gem, bundler will not update a dependency of that gem if another gem still depends on it. If bundler needs to update a gem that another gem depends on, it will let you know after the update has completed.If you want to update every gem in the Gemfile to the latest possible versions, run: and your test suite in your back pocket.